GSW: 1987
MEETING MINUTES
THE
GEOLOGICAL SOCIETY OF
January 14th
1987
Vice
President Douglas Rumble III called the 1158th meeting of the Society to order
at 8:07 PM. President Richard Fiske,
observing a tradition established by his predecessors, missed the first meeting
of his term on the flimsy excuse of participating in the Diamond Jubilee
meetings of the Hawaiian Volcano Observatory, and associated field trips.
The
following visitors were introduced: Adel
Asem, Kuwait Institute of Scientific Research; Joel Kimrey, Water Resources Division of the USGS, Orlando,
Florida; Diane Cameron, University of Maryland; Ann Post, Smithsonian
Institution; Steve Spradlins, apparently of no fixed
address: Ellen Cambe, Virginia Division of Mineral
Resources; and Susan Sherwood, National Park Service.
Not one to
be cowed by a preposterously ponderous podium, Leanne Milton, Chair of the
Public Service Committee, announced the National Science Teachers Association
Meeting to be held in
Leannes's second announcement was that GSW is auctioning
off a field trip to
The final
public service announcement was that planning is underway for a seminar on
Careers in Geology to be held at the Fairfax Public Library. Please see Leanne Milton if you would like to
volunteer.
The first
speaker of the evening, Dennis Krohn, began his talk,
entitled "Ammonium in mineral systems - oddity or commodity," by
telling us that the first ammonium silicates were described fewer than twenty
years ago, and that advances since then have come slowly.
Krohn used his studies of some selected ammonium silicates,
namely buddingtonite, alunite,
and illite, to bring us up to date. Describing buddingtonite
as an ammonium feldspar having no distinguishing features in hand specimen that
would divulge the presence of NH4, our speaker allowed as how the
good stuff must be seen in infrared - actually, the near-infrared. In alunite, NH4
can substitute for potassium, but again, the presence of ammonium can't be
detected in hand specimen. You guessed
it - infrared tells all. For example, by
plotting reflectance versus wavelength, ammonium is directly related to the hydroxy bonds in potassium alunite. It turns out that wavelengths of 2.0 and 2.1
indicate the absorption band values for ammonium.
Well, in
what kinds of environments can we expect to find ammonium minerals,
keeping in mind the ammoniah products are
usually kept directly beneath the kitchen sink?
Examples of
two of these three environments came next.
Some old hydrothermal hot springs at Ivanhoe, Nevada, were active in the
Tertiary and left some goodies behind, like mercury, which was once mined, and
disseminated gold, which was not, although lotsa
drill holes were punched in the ground in the hope the gold would be
economic. Armed with a radiometer to
pick up the 2.0 and 2.1u absorption bands, Krohn was
able to construct the first map of ammonium minerals ever made, by using said
radiometer to detect NH4 at the surface. His map showed the ammonium minerals occur at
relatively restricted localities, and their occurrence pattern is very patchy,
with no halos present. Krohn interprets his map pattern of patchy distribution,
sans halos, to indicate structural control rather than an all-pervasive
bake-off event by the
Superimposing
the microprobe onto his feldspar samples from Ivanhoe, Krohn
teased out some information about the sequence of ammonium silicate mineral formation
there. The feldspars are late stage,
whereas alunite is etched, indicating alunite formed early, and was altered later. So in this Tertiary hot spring deposit with alunite and feldspar both present, we have two different
chemistries at two different times. The alunite also has less ammonium than feldspar, but even
though the quantity is small, it's stable over a long interval of geologic
time, since even as long ago as the Ordovician.
Krohn described a second environment involving heat - the Cumnock Formation in the
Krohn synthesized his results from the Tertiary
So in answer
to the question, are ammonium minerals an oddity?, the answer is definitely
no. And even though they were found with
disseminated gold at Ivanhoe, they're not exactly a commodity, either. Our speaker concluded with a safe,
middle-of-the-road statement that the answer is neither oddity nor commodity,
but somewhere in between. Questions by
Howard,
The second
paper, "The Cambrian face of Iapetus," was
by Robert Neuman, USGS, and Michael Max, U. S. Naval
Research Laboratory. Claiming he had
drawn the short straw, Max began by saying the main point of the talk was to illustrate
regional approaches in solving geological problems; and that he was really just
discussing the Cambrian face of Iapetus in
passing.
In reviewing
some of the approaches traditionally used, such as accretion at the edges of cratons, and global plate tectonics, Max made a pitch for
unraveling mobile belts by the study of terranes. Defining a terrane as a body of rock that is
a coherent tectonostratigraphic unit which is bounded
by shear belts, he pointed out the advantage of not having to worry about
a model in which things are either framed, or suitably ignored.
The terrane
Max has in mind is virtually the entire North Atlantic today, with pieces of it
scattered around in
The
beginning of this scenario was Neuman's discovery of
the Penobscot event in
Moving away
from
Moving a bit
south to southeastern Ireland where some granites are mapped as a series of
pinch-outs, we can see from these that there are some major structural features
without having to know the details. Max
says they're wrench faults, and once we get to this level, we can look at major
shear boundaries annealed by the granite, which then lock the terranes. So in
Over in
In a grand
summary slide, Max took us from the mid-late Proterozoic,
when all these pieces were together, to the lowermost Ordovician, when Iapetus was there instead.
In the beginning, the mid-late Proterozoic, a
single unbroken continental crust included Greenland, North America, the
northern part of
In the late
Middle Cambrian subduction is still going on and the ophiolites
are winding up in the same general area, mostly concentrated in
Finally, in
the lowermost Ordovician, Iapetus is
established. A final gasp of the Caledonide orogeny produced a lot
of thrusting up in
Our third
speaker of the evening, Jeffrey Post of the Smithsonian, who is co-author with
David Bish, Los Alamos, took us on a foray to the
dark side in his talk, entitled "Manganese oxide minerals: some new
insights from powder x-ray diffraction."
Describing manganese oxide minerals a having a plus four oxidation state
and almost without exception being brownish-black in color and massive in
texture, Post admitted their one advantage is that one never has to argue about
which specimen is exhibit quality material - they all look alike. In fact, for years the problem of
distinguishing between various manganese oxides in hand specimens have been
solved by determining how dirty ones fingers became while fondling the
sample. By using this low-tech test,
not-so-dirty fingers designated "psilomelane,"
while filthy fingers were diagnostic for a manganese oxide bearing the
improbable name of - get this - "wad."
With our attention
on manganese nodules from the ocean floor taking on more serious overtones as a
source of manganese ore, it is worth our while to note these nodules are 40%
manganese oxide. An understanding of
these great, heavy, lumpy minerals just might help us to fathom the origin of
the sea-floor nodules. Unfortunately, a
problem with these grungy, massive-textured specimens is that one can't use
high tech stuff like x-ray diffraction or single crystal neutron diffraction. Nor will any specific information be divulged
by infrared or electron microscopy. So
what's a crystallographer to do, when faced with all this adversity?
New
technology and CHUTZPAH, that's what! It
turns out that some folks have used a high-resolution TEM in conjunction with a
new powder x-ray diffractometer with some credible
results. Post and Bish
seized upon this technique, pulverized some todorokite,
and subjected it to a high-resolution TEM.
Now, Post considers powdered x-ray diffractometry
to be a poor second cousin to using single crystals, but when you're working
with grunge, single crystals are a pipe-dream, anyway. The high-resolution TEM works fine for
identifying simple structures, but when it comes to the details of these
structures, the TEM, like your everyday manganese nodule, is in over its
head. Sadly it turns out there are no
completely resolved reflections in the pattern of the powered x-ray sample of todorokite.
Now its time
for the chutzpah part. Post hotwired the
Dutch Rietveld method. Instead of trying to separate
each peak in the powdered x-ray pattern, he chose to deal with the pattern as a
whole, and to treat each data point in the pattern as an observation. Starting out with a model of what he thinks
the crystalline structure looks like, Post used as variables both atom position
and occupancies, each of which were varied so that they best fit the observed
pattern of the powdered x-ray sample.
Another
factor in this game of "Outguess the grunge" is a long-standing
controversy about todorokite, over whether it was a
layered structure or a tunnel structure.
Enter Shirley Turner with her TEM to show it was a tunnel structure held
together by a triple-octahedral chain network, analogous to chains of silica tetrahedra.
Reminding us that with the TEM, simple structural framework is no
problem, Post told us the framework contained sodium, calcium, water, and in
deference to Dennis Krohn, the first speaker, even
some ammonium atoms. But where were
these things sitting in the tunnels?
Let's grab some samples and find out.
Post used
two specimens of todorokite, one from
Putting in
atoms whenever the pattern said things weren't very tidy, Post then calculated
the difference between the observed densities and his hypothetical ones. Fiddling around with different combinations
made things look even better. By using
the principle that greater electron density meant the greater the occupancy of
atoms, Post focused on the peaks and made maps of the differences between
observed and calculated values. After
superimposing the difference maps onto a plot of the framework structure, a
tunnel you will recall, Post and Bish were more than
pleased with the results. Not knowing
whether what they were seeing was an artifact or real, they tried the same
thing on the
So after
years of mineralogists messing about with such filthy, grungy rocks, there is
light at the end of the tunnel, after all.
Questions by Stewart, Freeborn, French, and Sorensen.
There being
no other business, Vice President Rumble adjourned the meeting at 9:47, and
eighty members made for the refreshments.
THE
GEOLOGICAL SOCIETY OF WASHINGTON
1159TH
MEETING
January 28,
1987
The 1159th
meeting of the society was called to order by Vice President Rumble at 8:10 PM,
culminating a week that gave us twenty-plus inches of snow in storms on either
side of Super Bowl Sunday. The WEEK THAT WUZ featured OPM's abominable snow plan of the preceding Thursday, a
Metro system that was frozen in its tracks, below-zero temperatures, and seven
straight snow days in Fairfax County schools.
Things were so bad that Mayor Barry called in sick from California, but,
GSW met on schedule. With parking
at a premium, and the Metro system on its knees, Vice President Rumble wished
the minutes to state that only the bravest and truest of the GSW membership was
able to get out. The audience gave
itself a round of applause, whereupon Rumble remarked, John Wesley Powell must
be beaming proudly, wherever he might be.
Vice
President Rumble then announced the death of Vincent E. McKelvey, Director of
the USGS from 1971 through 1978, and all present stood for a moment of silence.
One visitor,
Mark Bagantz of Howard University Medical School,
introduced himself, remarking that his switching from graduate school in
geology to medicine was a tough choice, but then he had to consider the
prospect of survival after acquiring the sheepskin.
In an
informal communication, Ralph Haugerud showed us what
can be done with a mass spectrometer in trying to unravel some messy results
from potassium-argon dating. Mentioning
a publication that said some K-Ar spectra are uninterpretable, Haugerud pointed
out that instead of assuming the sample contains only its original argon composition
plus whatever baggage it acquired from decay of its potassium, we should ask
whether the argon present might not be the result of mixing between the crystal
and some reservoir we don't understand.
Questions by Phelps Freeborn, Michael Max, E-an Zen, and Dave Stewart.
For the
first talk of the evening, Glenn MacPherson took us
"Chasing seamounts in the northern California Coast Ranges." Starting off by telling us there is an easy
way and a hard way to look at submarine features, MacPherson
reminded the audience of Robin Brett's glamorous pictures taken from the Alvin
of the pretty stuff to be seen on the sea floor. As an aside, our speaker pointed out that
Brett's talk tended to downplay such unpleasantries
as lost gear and seasickness. And even
though fresh pillow lavas might be thin-skinned, MacPherson
doubted they were thin enough for Brett to see through. Then, taking a firm stand for doing field
work with his feet steadfastly planted on solid ground, our speaker ventured
that all things considered, walking an outcrop was a better way to do things
than scooting through the darkness in the Alvin.
To prove his
point, MacPherson showed us slides of subaerial outcrops and sent rejuvenated chills down our
spines with a detailed analysis of a place called Snow Mountain, of all
things. Déjà vu the WEEK THAT WUZ! Snow Mountain has a pile of rocks 2 km thick
that start off at the bottom with clastic sedimentary rocks loaded with
radiolarian tests that haven't been able to make up their minds about how old
they are. Diabase
dikes intrude the clastics and grade up into pillow
lavas. Brecciation in the lavas
increases upward, indicating the volcano was becoming more explosive as it
grew. Above the brecciated pillows some
more pesky radiolaria separate the lower series of
volcanics from an upper series that look like pahoehoe
flows this time, not pillows, but with still more brecciation. Then for good measure we get some graywacke capped by the West Summit series volcanics, the
youngest of which are rhyolites. MacPherson believes
the rhyolites suggest a differentiation trend typical
of islands and seamounts, rather than mid-oceanic ridge basalts. Questions by Daniel Milton, Tom Dutro, Ralph Haugerud, and E-an Zen.
John D.
Unger, USGS, presented "Deep structure of the Northern Appalachians in
Maine and Quebec: results of deep
seismic reflection experiments," the second talk of the evening. Alleging that tonight's talk was not a
complete summary of what his group has been doing, Unger then unabashedly
flashed a slide that revealed a complete seismic reflection study across the
northern Appalachians from SE Quebec to the edge of Georges Bank. Not only did they run said seismic reflection
studies (which were compared to the spanking-new geologic map of Maine), they
also did a refraction study in conjunction with their reflection lines. By throwing in a wide-angle reflectors, as
well, they could construct a 3-D model of the crust. Gravity studies helped to round things out.
These guys
focused a lot of their attention on the Merrimack synclinorium,
not to be confused with the golden double anticlines of a Big Mac
emporium. They found the crust thinned
significantly from northwestern Maine down to the coast: from a thickness of 40 km down to 10, and that
the Moho was a remarkably planar feature. The Moho in
Maine stays mainly in a plane! A
thrust fault, the Norumbega, forms the contact
between the rocks of the Merrimack synclinorium and
those of an older coastal antiform. The Cushing and Cape Elizabeth formations of
the antiform are overlain by the thrust sheet, and
the fault contact was traced to a depth of 10-12 km, where it marked the bottom
of the synclinorium.
In central
Maine, gravity studies revealed a steep gradient in the murky depths below. Luckily, two Devonian plutons
were in the vicinity, and they could be conveniently connected at depth like
Siamese twins to produce a model which fit the data. Further east, a high-density feature at depth
was not as easy to pin down. The anomaly
was near the Moho, but with a density that was too
great for the Moho to account for its magnitude. Nor was there any outcrop of mafic intrusions
to come the rescue this time. Lacking
any tangible evidence for this high-density feature, Unger suggested it may be
a down-east aggregation of Mesozoic intrusives at
depth. A-Yup! Questions by Bill Burton, Dave Stewart, a
co-author, no less (twice), Norm Hatch, Gene Robertson, and Bill Greenwood.
Brooks
Hanson, Smithsonian Institution, finished up the evening with his talk,
"Mechanics of low pressure metamorphism:
Numerical models and evidence from the Cordillera." Starting off with the question, "Does magmatism cause low pressure metamorphism?," Hanson
gave us at least forty minutes worth of information in half that time. He answered his own question by observing
that rocks can get metamorphosed in the upper part of the crust, a place where
temperatures ordinarily are lower, by one of two ways. Either a single massive intrusion can elevate
the temperature in country rocks just that one time over a wide area, or many
smaller intrusions can succeed one another over the same area until they appear
to be juxtaposed into one bloody big batholith. Sort of like the difference between a shotgun
blast and the life history of a pincushion, taken one poke at a time.
Getting us
into a receptive mood by showing a spectacular slide of the Sierra Nevada batholith, Hanson explained that we were looking from White
Mountain Peak to Mount Whitney, 100 km away.
Although most of these rocks have experienced low pressure metamorphism,
we were told that the slide covered three different magmatic
arcs over time, and the full width of the metamorphic field spans about 180 MY.
Does mother
nature fit the numerical models? I'll
bet not, if she doesn't understand cylindrical coordinates! If the computer fills up the crust with
enough granites, Hanson says the wall rocks never forget, and will integrate
all these higher temperatures over time.
The numerical models show the pressure-temperature pattern in the
country rock is defined by the array of intrusions, a result which must have
been reassuring to the programmer. Our
speaker concluded that regional low pressure metamorphic mineral assemblages
will form at pluton densities of greater than 50%,
the point beyond which lots of little intrusions over time really can look like
one humongous batholith.
Two
questions by Ralph Haugerud revealed that he, for
one, did understand cylindrical coordinates. He got our speaker to admit you can't generalize
from models of a single pluton to a multiple model by
using cylindrical coordinates, but you could in a cartesian
model. As Haugerud
and Hanson both have Scandinavian surnames, the question was really one of
Descartes before the Norse.
With an
invitation to the 41 brave and true members to return on February 11, Vice
President Rumble adjourned the meeting at 10:01 PM.
THE
GEOLOGICAL SOCIETY OF WASHINGTON
1160TH
MEETING
February 11,
1987
The 1160th meeting
of the society was called to order by President Fiske at 8:02 PM, and in the
remarkably short span of two minutes, most of the assembled visitors, guests,
and members, including those in good standing and those in arrears, had taken
their seats and had achieved a semblance of decorum. The minutes of the previous meeting were
approved as read. Six visitors were
present, three of whom unabashedly introduced themselves. Mike Phillips of Florida said he was here
looking for a job (there seem to be a lot of that going around lately). Anders Asland and
Marcus Key both are at the National Museum of Natural History. The three others who were introduced are Yang
Chi Qing, The George Washington University, Lisa Helton, Howard University, and
Christian Repetski, who was celebrating his first
birthday by having his diaper changed elsewhere in the Cosmos Club. Only one year old, and already this kid is in
arrears.
The names of
six newly elected members were announced:
Alan Driscoll, Jr., Patricia Watterson, Barbara Eisworth,
Steven Shirey, Susan Sherwood, and Christopher Beza.
On behalf of
the Public Service Committee, President Fiske announced that the schedule for upcoming
science fairs was now available for those who were to be judges, and that GSW
will present Walter Sullivan's book, Land Prints, to the various science
fair winners. John Repetski
asked about the fate of a GSW member who had been auctioned off on radio
station WETA. Leanne Milton replied that
WETA got the money GSW got the publicity, and that Rob Weems, the auctionee, will get to lead a field trip in the spring.
Daniel
Appleman gave the first of two informal communications dealing with fire and
ice by reading us a hot flash from Antarctica where the Joides
ship, Resolution, is basking in the austral summer. Breathlessly reading us communiques
radioed from the ship, straight from the poop deck as it were, Appleman
reported on drilling at two sites near the Maud Rise. The first drilling site penetrated to within
30 meters of the basement and yielded sediment cores loaded with
microfossils. These sediments show a
remarkable lack of reworking, and the KT boundary comes complete with volcanic
ash, which, together with the microfossils, provide plenty of ingredients to
play the dating game. Fortunately, the
KT boundary coincides with those elsewhere, and even as Appleman spoke the
microfossils were busy providing the southernmost anchor of Cenozoic biostratigraphy.
Site two bored deeper than site one, through 320 meters of sediment,
into the basement this time, which was a basalt loaded with vesicles and amygdules. On the
way down the KT boundary was encountered once again, still marked by volcanic
ash, and still coinciding with those found elsewhere. The only questioner, Dan Milton, wanted to
know who was determining that ash, anyway, some paleontologist? Matches, matches, M-A-T-C-H-E-S. Matches, matches, M-A-T-C-H-E-S. You can strike 'em
on paper, strike 'em on glass - I once knew a man who
could strike 'em on his ASH-can; Matches, matches,
M-A-T-C-H-E-S.
The second
informal communication, dealing strictly with fire this time, was given by Bob
Tilling, who, along with our wayward president, was just back from some
hi-jinks in Hawaii. Under the guise of
participating in the Diamond Jubilee seminars of the Hawaiian Volcano
Observatory, throughout the month of January, and, with the dedication of a new
building thrown in for good measure, Fiske and Tilling almost had us fooled
until the first slide. These two really
let it all hang out doing a hookey lau in concert with Dallas Peck, Tom Wright, and William P.
Mott, the head of the National Park Service, all aided by an even more motley
assortment of native dancers. In an
effort to put an honest face on this boondoggle, Tilling showed a magnificent
slide of a sky-high lava fountain that dwarfed a helicopter in flight. WAIT!
Was this venerable band of dancers really being choreographed by Ponce
de Leon? The continuing eruption of
Kilauea, which began in 1983, added 250 meters of material above the 1983
surface before the high fountains changed to lava lake activity last July. Small degassing fountains around the edge of
the lake still managed to provide plenty of challenge to the intrepid
geologists gingerly doing their sampling among the fountains, provoking feats
of agility some probably weren't aware they had! Perhaps Ponce de Leon didn't desert this
clambake after all!
Lava tubes
allowed lava to reach the sea around Thanksgiving for the first time since
1973. Owners of the 29 houses consumed
en route are probably not as thrilled as geologists are by the fact that the
lava added 18 acres of new land to the sea in about two week's time. There goes the neighborhood! Questions by Ralph Haugerud,
who wanted to know how the new shield got shorter as it grew, Dieter Johnson,
E-an Zen, and Roz Helz, who offered a comment that the small degassing
fountains surrounding the lava lake still serve as chimneys to release the
volatiles. Moto
Sato said he had been ready to say what Roz just said, and then he said it
again.
The first
formal talk of the evening may have provided a first for GSW, with Jack Epstein
billed as speaker, with one asterisk, and Peter Lyttle
as answerer, with two. Epstein deftly
saved himself from a pratfall as he tripped to the podium, and then, with great
panache, he leaned on the sympathies of the audience as he pleaded
laryngitis. Rasping an appeal to help
him conserve his flagging vocal cords, he asked the audience to say AAH, on
cue, followed by a languorous OOH. While
the speaker was busy trying to further mesmerize the audience, the
two-asterisked answerer remained silently glued to his seat.
Finally
getting to the heart of it, Epstein said he was really going to talk about the
chronology of deformation in the north-central Appalachians, and its
significance, or, the mystery of the Taconic hiatus deposit.
For those
who just came in, the base of the nitty-gritty Shawangunk
Conglomerate of Middle Silurian age unconformably
overlies the more shaley Martinsburg Formation, a
thick pile of marine rocks which are Upper Ordovician. The Taconic angular unconformity between the
two spans about 30 MY and stretches 128 miles from the Taconic allochthon in New York to the Hamburg Klippe
in Pennsylvania. Ever since H. D. Rodgers
identified the Taconic angular unconformity in 1838, geologists have been
debating about just exactly what happened to which of these rocks where, and
when. After having poked in the nooks
and crannies of this unconformity, our speaker said not to worry. Summarizing the features at four nooks and
three crannies, he told us the Martinsburg rocks beneath the Taconic angular
unconformity (1) are beveled at an angle that varies from 2-15 degrees, (2)
experienced their dominant folding during the Alleghenian
orogeny, and (3) have Taconic cleavage with an Alleghenian overprint.
Also, the Taconic folds are broad and open, and the Taconic trends are
more northerly than those of the Alleghenian.
The best
part was yet to come. Epstein wanted to
know what else went on during the 30 MY hiatus while the Taconic angular
unconformity was being eroded, and went in pursuit of the Taconic hiatal deposits. For
one thing he found diamictite that apparently was the
product of mass wasting. At Mount Menago, New York, there is a shale chip gravel deposited on
the Martinsburg surface, reminiscent of a Pleistocene chip gravel, together
with some colluvium consisting of silt and clay. Convolutions in the bedding, together with
slump features suggest frost heaving, and fortunately a glacial center was not
too far away in the Ordovician. Some
cobbles of laminated quartzite in the hiatal zone
have weathering rinds, indicating exposure to air. And finally, slickensides in the Martinsburg
are associated with another diamictite, which our
speaker says is fault gouge.
So, from
whence have these rocks in the hiatal zone come? From the Passaic Formation of speculative age
to the northwest, that's where. When the
marine Martinsburg was uplifted during the Taconic orogeny,
the Passaic Formation was weathered and then produced clasts from a source that
is now nowhere nearby. Said clasts piled
up to become the hiatal deposits anytime from, say
equivalent to the lower Martinsburg, to perhaps the Upper Ordovician. All this was sounding pretty good until
Epstein told us the source area had long since been eroded, along the Taconic
thrust sheets.
So here we
have a 30 MY hiatus, separating rocks that were ruptured by Alleghenian
cleavage. With a hiatal
hernia of that magnitude, I say forget about Epstein and Lyttle,
it's in God we TRUSS! Questions by Anita
Harris John Repetski, and E-an Zen, who wanted to
know if an official answerer was the same as an official spokesman. The official answer from Peter Lyttle was an emphatic, NO!
The second
scheduled talk was not given because the speaker, Michael Cline, had been
called out of the country.
Stephen
Phipps finished up the evening with his talk, "Style and tectonics of
re-activated basement structures, U. S. mid-continent." Telling us that he would stick to the facts,
then generalize, and not enumerate, Phipps projected a map of the southeastern
United States showing more than 25 numbered structures, and proceeded to
enumerate their virtues.
Phipps
launched into the four types of structural styles he recognized. Leading the pack was the Wichita frontal
fault system of Oklahoma. Here, the
basement faults were thrust over the Anadarko basin for all to see. The Tishomingo Block in the south Oklahoma allochthon contains a deep sedimentary basin with what
Phipps calls propeller faults - certainly a unique approach to moving rocks
from one place to another.
But, keeping
abreast of technology, Phipps abandoned propellers for a jet to show us a view
from six miles above the Arbuckles. From this vantage point we could see a
steeply dipping forelimb, a flat top, a gently dipping backlimb
flattening out to zero dip, and finally the whole thing runs into another
structure. The fault upon which the Arbuckles are riding flattens out at depth, a feature
Phipps calls sled runners. Jingle bells,
jingle bells, jingle all the way. Oh
what fun it is to ride a thrust fault every day.
The second
kind of structure is a basement-cored asymmetrical anticline as seen in the
Nemaha Ridge of Kansas. With structural
relief of less than one km and Emporia stuck smack in the middle, it's no
wonder Horace Greeley told the young folks to head west.
The third
kind of structure is a basement fault overlain by a whole series of en-echelon
faults, which could be formed under the influence of lateral shear. Forsaking propellers, jets, and sled runners,
our speaker said a small right lateral fault with motion of one km is enough to
do the trick. Turning the screw in his
own way, it was about here that Doug Rankin registered his first officially recorded
snore of the 1987 season.
The fourth
and final kind of structure is produced by re-activated normal faults such as
seen in the carbonates of Natural Bridge State Park, Kentucky, where
Pennsylvanian limestones are against Mississippian clastics.
Phipps now
asked the rhetorical question, are there structures like this in other orogens of the world?
Of course the answer was yes, with examples of re-activated thrust
faults in the Alps and Paris Basin, and a re-activated normal fault on the Isle
of Wight.
But the Alleghenian orogeny provided
Phipps' pièce de résistance. He assumed
the Appalachians were rigid blocks moving independently of one another. The deformation we see is at the boundaries
of these crustal blocks, and Phipps coined the term,
"crustal mesoplate
tectonics," to describe what had gone on.
He blamed it all on failed rifts, with an original collisional
orogen somewhere off to the side. Dêcollement could
be explained by detachment of the rigid upper crust from weaker stuff below,
and failed rifts could provide magnificent avenues for magmas. But, Phipps was no Phineas
Phogg, for even though he used propellers, jets, and
sled runners, he finished four minutes over the 20-minute mark. Questions by George Helz, Bill Berg, Ben
Burton, and Sorena Sorensen.
President
Fiske requested that the 25% of the membership in arrears please pay their
dues, and announced the program for the next meeting. The meeting was adjourned at 9:38 PM, and
attendance was 74 members, ALL in good standing - of course.
THE
GEOLOGICAL SOCIETY OF WASHINGTON
1161ST
MEETING
February 25,
1987
The 1161st
meeting of the society was called to order by President Fiske at exactly 8:00
PM, catching everyone by surprise. Rising
to the challenge, the audience was fully seated by 8:01, beating last meeting's
time by a full minute. The minutes of
the previous meeting were read, and read, and read. Although neither approved nor disapproved,
they were blissfully terminated. Six
visitors and guests were present: James Hertzler, Will Lamb, Jonathan Freese,
Kevin Howard, Sam Adams, and Ann Brewster.
Leanne
Milton, chairperson of the Public Service Committee, announced the need for 15
volunteers for science fairs between March 14 and April 4. And for the National Science Teachers Association
Meeting to be held in Washington March 26-29, one volunteer is needed to help
man the booth being co-sponsored by GSW and the Naturalist Center of the
National Museum of Natural History.
In an
informal communication, E-an Zen alerted the membership to the potential for
their being listed as a co-author without their knowledge. Citing the January 15 issue of Nature,
in which Stewart and Feder dissect the scientific
papers of one John Darsee, a confessed forger of
data, Zen went on to say that Stewart and Feder
questioned to what degree Darsee's 47 various and
sundry co-authors shared in his fraud.
For example, in the biological sciences, honorary co-authorship is
common for those associated with the laboratory whose facilities were involved
in the research. Zen suggested that
co-authorship without contribution could lead to distortion. Further, Stewart and Feder's
claim that the threat of a libel suit against them for an earlier, unpublished
version of their Nature article actually constitutes a form of
censorship. Zen said he was placing the
situation before the group to see if this was a problem in the earth
sciences. Comments by Phelps Freeborn,
Kathleen Krafft, Rosalind Helz, Daniel Milton, and
Richard Fiske.
For the
first talk of the evening, Fred Doyle exposed us to the "Large-format
camera on the space shuttle." Large
format in this case is no exaggeration, each frame measures 23 ´ 46 cm, twice the size of an aerial photograph. No instamatic, this outfit, complete with
stellar cameras and a terrain camera, needed no less that the space shuttle to
haul it around. Large format and LARGE
COST, Doyle says. Nestled in the cargo
bay of the shuttle and using slow-speed, fine-grained film, the terrain camera
takes pictures with 80% overlap, providing superb stereo coverage. The exquisite resolution we were yet to
behold.
Doyle took
us on a magnificent tour through the eyes of this system to let us see its
capabilities firsthand. We went from
Montreal to Cape Cod, where we were treated to a view that measured l degree of
latitude by 2 degrees of longitude.
Remarkable as that was, Doyle showed us we could easily get twelve
adjacent enlargements from a single frame, each enlargement at a scale of
1:250,000! From the overall view of
Boston and Cape Cod, one of these enlargements zoomed us in on a time-lapse
series of a passenger jet landing at Logan airport, captured with ease from
successive frames. Then on to the
Tibetan Plateau, Mount Everest, Katmandu, and Italy, where an enlargement
showed us Venice, its bay, canals, beaches, and ships; and our speaker swore he
could see a girl in a red bikini!
Quick to
dispel any notion that our photographers were voyeurs in space, Doyle now
revealed some of the camera's more sobering scientific applications. For example, Beijing has used an enlargement
of Mount Everest, complete with glaciers, to construct a contour map with
50-foot intervals. By setting up ground
control points ahead of time, as was done in the Black Hills test area by our
own boys, the large-format black and white prints can be combined with LANDSAT
imagery to aid in resolving 1:24,000 maps.
In fact, from an altitude of 225 km, which gives coverage of 170 X 340
km per frame, resolution from the large-format camera knocks the socks off LANDSAT's multispectral
scanner. Planning was underway to get
more of these amazing pictures from a polar orbit when the space shuttle
accident occurred last year. So for now,
it's "Goodnight, sweet prints."
Comments and questions by Jim Garvin, Keith McLaughlin, Gene Robertson
(twice), E-an Zen, Phelps Freeborn, and Alta Walker.
Curt Larsen
presented "Isostatic uplift in the Great
Lakes," the second talk of the evening.
Larsen reminded us that although isostasy is an everyday word today, in
the 19th century it was a highly controversial concept. G. K. Gilbert was one of the first to use isostatic adjustment in his explanation of the terraces of
Lake Bonneville. At the same time,
Thomas Crowder Chamberlain, a rigid-earther, was
totally opposed to the idea. So guess
who published the first Quaternary study of the Great Lakes region?
Noting that
a lot of today's Lake Michigan basin once contained glacial Lake Chicago, a
late Wisconsinan feature, our speaker told us that as
we head north, the depressed crust got deeper and deeper. James Goldthwait
came out from Harvard early this century to see for himself. He traced the terraces from the south end of
the lake, down where it drained toward Chicago, up north. When Goldthwait got
to Greenbay, Wisconsin, the terraces diverged; so he
postulated a hingeline to account for it. South of the hingeline,
nothing had moved; north of it, there was dramatic movement, indicating lots of
rebound. Gilbert, always willing to
help, had suggested that if one used lake-level gauge records, one could
determine uplift rates. Naturally he was
ignored by geologists, but heeded by engineers.
Larsen says
although Goldthwait's model acknowledged the drainage
southward toward Chicago, he missed the outlet to the north. But to be fair, Goldthwait
didn't have lake-bottom cores in which the horizon of red clays is a marker for
the last of the pre-glacial pre-glacial lake
surfaces. Our speaker told us glacial
lake Algonquin came after Lake Chicago and was many times larger, so that it
straddled the North Bay sill, and covered part of Canada. Canadian data show that the place where
former Lake Algonquin stood is higher up north today than it is on the south
side of the sill in Michigan. With
rebound, Larsen says, the North Bay sill eventually blocked drainage to the
north, and all the rivers were then pushed back to drain to the south into
Michigan. Moral: the best way to recover from a period of
depression is to go with the flow. A
question by Bob Tilling and a comment by Karen Prestagaard.
Ursula
Marvin finished up the evening with her talk, "The meteorite Ensisheim: 1492-1992
(almost)." This delightful account
began with the horrendous explosion heard in the Rhineland on November 7, 1492,
when the meteorite landed at Ensisheim. A true sonic boom, the explosion was heard
within a radius of 95 to 120 miles, depending upon whom one talked to. It was heard in the Alps, along the Danube,
and it caused the French to tremble.
Showing no such trepidation, souvenir hunters immediately started
chipping away pieces until the chief magistrate put a stop to it. Publicity and propaganda have kept the Ensisheim meteorite before us ever since. Fortunately, it fell about 35 years after the
invention of printing, so the occasion provided the prototype for media
coverage of a geologic event. Brandt put
out broadsheets complete with a woodcut of the stone coming out the sky, and simultaneously resting on the
ground. It had a German text paralleled
by one in Latin; cited the authorities (in this case Pliny, who lived 1400
years earlier), described the event, and concluded: "I don't know what it
is!"
As for the
propaganda, the advisors to Maximillian I,
Emperor-elect of the Holy Roman Empire, told Max the meteorite meant good
things for him. Maximillian
was spoiling for a fight with Charles VIII of France. In the following January, Max had his war and
won. He also agreed with the magistrate
that the meteorite should be protected from further vandalism, but only after
he took a few pieces for himself.
As time went
on, the meteorite acquired more and more status, in spite of the first chemical
analysis in 1800, which declared it to be a common, ordinary stone. In search
of a suitable repository, the people of Ensisheim
placed it in a church in 1804, which suited everybody just fine until the
church fell down. Now it is properly on
exhibit at the Hôtel de Ville, protected by two
officially appointed Guardians of the Meteorite, each decked out in a
flaming scarlet tunic and brandishing a medieval axe. But the most substantial way the Ensisheim meteorite is commemorated is with a local brew,
Meteor Bier. Questions by Moto Sato, Gene Robertson, and Dick Fiske, who wanted to
know why 1992 in the title? Marvin
replied that she still wasn't done with this, and besides, so far she's had
three trips to Ensisheim, at which point there was a
collective gasp from the audience.
Perhaps feeling the need to explain, Marvin said that way up into the
1770's they were still talking about this meteorite. One thing for sure, this lady really knows
how to go for baroque.
President
Fiske announced the program for the next meeting to the 91 in attendance, and adjourned
us at 9:54 PM.
THE GEOLOGICAL
SOCIETY OF WASHINGTON
1162ND
MEETING
March 11,
1987
You will
recall that four weeks ago tonight, the 1161st meeting of the Society was
called to order by President Fiske at precisely 8:00 PM, catching everyone by
surprise. However, the audience rose to
the challenge, and was fully seated and ready for business at 8:01. In stock-car racing jargon this nimble bunch
had an elapsed time of just one minute from beer keg to business agenda. At the last meeting, the 1162nd, our
president overcompensated and called the meeting to order at 7:59 and 30
seconds, really bending the cool of some of our more seasoned socializers. Amid
much grumbling, griping, and last-minute groping for enough liquid sustenance
to carry themselves through the opening moments of the meeting, our group again
settled down at 8:01, a remarkably consistent performance. Let this be a lesson to our leader, that to
prematurely withdraw warm and cuddly geologists from their source of suds, can
reduce these guys to a bawdy rabble.
It's OK folks, the spell is broken.
The minutes
of the previous meeting were read and corrected. Four visitors were present and duly
applauded: Ishio
Moriya, Japan: Mike Koska, University of Michigan:
John Perso, __??__; and Robert Lowell,
NSE. I still don't know what that
(NSE) stands for. The names of two newly
elected members were read: Kevin Howard,
USGS; and David Hawkins, The George Washington University. There being no announcements - not even one
more plea for science fair judges - we proceeded directly to the regular
program. The evening's fare sandwiched
an innocent oceanographer between two theoretical petrologists,
each armed with a PC. Armed, and loaded,
as it turns out.
For the
first talk of the evening, Ralph Haugerud spoke on
"Cooling history of the Nason block, Baja,
British Columbia." Haugerud explained the title by telling us that his area is
not in British Columbia at all, but south of there, like Baja is south of
California. The paleopoles
in this mountain wilderness are displaced and discordant. To explain why, our speaker offered two
possibilities. Either these paleopoles were tilted in place, rotating as they were
tipped, or, the entire region has moved northward since the Cretaceous, in
which case they could have come from as away far as Baja, California, along a
transform fault.
To decide
which was which, Haugerud chose the Nason block because it was a good place to do PT work on
aluminous rocks. Ages on hornblendes are
concordant locally, but in running 40 miles across the block, muscovites are younger along a line to the east. Various plutons
pierce the quiet solitude of this place, perhaps upsetting and resetting some
clocks in the rocks. Varying degrees of
metamorphism tend to cloud the regional history even more, but in an elegant
synthesis direct from his PC, Haugerud showed us what
he thinks happened. An analysis of 21
argon dates indicates the younger ages to the east are produced by release of
strain, not by reheating. If the igneous
hornblendes date an initial rapid crystallization of the pluton,
then the lower temperature micas could be recording a later cooling event,
which was slower. The younger K-Ar dates to the east can then be explained by an unroofing event in the Cretaceous, followed by tilting up
to the NE in the Eocene. The alternative
is to assume the discordant mica dates are from atmospheric argon contaminating
the sample, which isn't half as much fun.
Haugerud says that tilting the Nason block isn't enough to give us the discordance we see,
so there must have been some transport, too, even if it wasn't from as far as
Baja. I still think that stripping off
the overlying rocks is an a-peeling solution.
Questions by two others who have PCs; Brooks Hanson and E-an Zen.
Ellen Kapell, the innocent oceanographer, presented
"Volcanic episodicity and a non-steady-state
rift valley along the NE Pacific spreading centers: Evidence from the Sea-MARC I, Seabeam, and deep-sea photography. You remember, Ellen, she's the spunky lady
who tried to set Robin Brett straight on the details of an Alvin dive during
his presidential address. Ellen should
know - she's mapped the equivalent of five quadrangles down there with the help
of fancy gear like Seabeam and Sea-MARC. The Seabeam system
attaches to the hull up front to give swath-map bathymetry with its 16
eyes. Sea-MARC gives bathymetry too,
from deep sonar towed behind the ship.
Now how can you beat a system that not only tells you where you're
going, but where you've been? With a
sled from Lamont, complete with underwater Limpus
camera, and a Panasonic video, that's how.
Even though they started out just to make the bathymetry better, and did
(by producing a contour map with a 5-meter interval), Ellen says it's the
photos that tell us all about the really good stuff luring in the murky depths
below.
In the Juan
de Fuca ridge system, she believes there is evidence for a non-steady state
condition at the site of the rift valley, AKA the elongate summit depression,
or ESD. For example, Ellen showed us
fresh flows on the flanks of the ridge crest.
Some of these flows wound up on the floor of the rift valley, or ESD,
where they show more fracturing and faulting than their outboard complements on
the flanks. And we saw a volcano that is
shaped like an archer's bow in plan view instead of line an upside-down
ice-cream cone as it should be. These
things, she says, are evidence for collapse followed by extension, rather than
for steady state. Whatever is going on
down there, I don't see how this place can look so rugged, and yet be so
peaked. Questions by George Helz, Moto Sato, and Joe Boyd.
While
introducing the final speaker, E-an Zen, President Fiske reported that E-an
earned his BA degree from Cornell - he thought sometime in the Silurian. Zen, the second wild and crazy
speaker on the program with a PC, followed up on Ralph Haugerud's
model and talked about "One-dimensional models for progressive partial
diffusion." I'm not sure how he got
from no rocks at all, to stacks of thrust sheets producing incubation and
warm-up at depth, then through a slew of graphs, to get plutons
that look like polliwogs, both in Nepal and Massachusetts. Zen says the bulgy part of these tadpole-shaped
plutons is what was intruded as a result of partial
fusion, and the tail is what was left behind.
He did! A sure case of the tail
wagging the wog.
Heavy grilling by a shirt with brown stripes and Gene Robertson.
President
Fiske announced the program for the next meeting to the 67 in attendance, and adjourned
us at 9:35 PM.
THE GEOLOGICAL
SOCIETY OF WASHINGTON
1163rd
MEETING
March 25,
1987
The 1163rd
meeting of the Society was called to order by President Fiske at 8:02 PM, and
the audience was ready for action at 8:03.
The minutes of the previous meeting were read and corrected. Eight visitors were present: George Blufort, a
tan sport coat who mumbled, Vince LaPiana, Peter Eisington, Rong Jai-yu, Shi Xiao-yin, Jonathan Freese
(who has been here before but hasn't joined yet), and Emma Booy. The Spring field trip to Calvert Cliffs was
announced for May 9, and President Fiske put in a plug for all dilatory and
delinquent members to PLEASE pay
their dues. You know who you are.
Bruce Wardlaw, wearing a woolen cap from Swat, gave the first of
three informal communications on his recent field work in Pakistan. Bruce, always a high-stepper, had to really
lift his feet to get at the Permian fossils this time. The Pakistani officials in charge saw Wardlaw coming, and in honor of his visit they released a
torrent of water into a stream which lay between the end of the road, an his
outcrop. But it was worth it all for the
open-air cooking in a six-foot wide fry pan, and besides, the Smithsonian was
paying. In the second informal
communication, Bob Neuman told us about some
brachiopods the Chinese have newly reported from (1) Mount Everest, (2) north
China, and (3) south China, that closely resemble an assemblage of Ordovician brachs from Newfoundland.
"Have rofophore, will travel." Phyllis Renzetti
concluded the informal communications with a tour into conjecture land
vis-à-vis the geologic time scale.
Having duly noted there is a periodicity of events in the Phanerozoic; you know, things like transgressions,
regressions, and extinctions, Renzetti decided to
talk about what she termed "circular time." She says it looks as if the world still goes
'round and 'round in an elliptical orbit, just as it usta,
while all the time the earth and sun jiggle up and down out of phase with one
another like horses on a merry-go-round.
No wonder us passengers on spaceship earth get dizzy while we're being
spun dry, ying-yanged, and yo-yoed.
For the
first formal talk of the evening, Trent Haselton
asked the question, "Does the presence of fluorine significantly affect
mass transport in high-temperature hydrothermal solutions?" Noting that the presence of fluoride in
low-temperature aqueous solutions, ie., municipal
water supplies, significantly reduces the probably of tooth decay, Haselton suggested the cavities and fractures in wall rocks
surrounding a silica-rich magma in its waning days might also benefit from the
presence of fluids containing fluorine.
But of course. Fluoride lowers
the viscosity of melts, as well as aiding in the transport of major cations in the fluid phase.
Not only that, but silica solubilities are
enhanced a whole lot by the presence of fluorine, and apparently fluorine complexing has a great deal to do with potassium activity
and the concentration of aluminum. In
fact, Haselton says straight alkali complexing is not very important at all because the complexing of silicon and aluminum takes care of
practically all of the fluorine. So if
you're a cavity in wall rock and the fluoride's all gone, there's nothing else
to do but say, "Fangs for the memory." Question by Sorensen.
Michael
Cline presented "Methods and problems associated with assessing earthquake
hazards in Central America," the
second talk of the evening.
Unfortunately for Central America, it lies upon the Caribbean plate on
the lee side of a subduction zone, and it catches a lot of grief as the Cocos plate bumps and grinds down into the Central American
trench. Recent earthquakes in El
Salvador, Guatemala, and Nicaragua have been grisly affairs, producing death
tolls of 2,000, 30,000, and 18,000, respectively. The song says Managua, Nicaragua, is a
wonderful place, but the 1972 earthquake was particularly devastating as it
occurred at Christmastime, destroying 60% of the structures and damaging
another 30%, leaving only 10% intact.
The city burned for five days and the government was inoperative for a
lot longer. By 1975, Managua was finally
cleared of debris and a major decision was made for the government to remain
there. Rampant development around the
perimeter of the cleared area indicated a real need to organize before all the
dangerous places were covered with buildings again. Enter Roy Weston, Inc., and our speaker,
wearing white hats. They looked at the
historical seismicity, air photos, side-looking
radar, low-sun-angle photos, and checked it all out from the air. On the ground they constructed trenches
across the fault zones, and established trench logs, some of which could be
dated. From all this they were able to
map 17 active faults in Managua, and to establish the slip rate on quite a
few. The good news is that Cline and
company are now embarking on similar investigations in Costa Rica and San
Salvador. Questions by a brown jacket,
Bill Howbrick, Gene Robertson, E-an Zen, and Debbie
Juarez.
Donald LaMar, of Zip-A-Dip Protractor Co., and USC, finished up
the evening with his talk, "Tracking J. Tuzo
Wilson's elusive North American transform." But not before LaMar
gave a silent commercial for Zip-A-Dip by showing us his blazer was reversible
by wearing it inside out, revealing all kinds of nifty slogans for Zip-A-Dip,
and lots of pockets to hold his wares.
Soft sell, to be sure. But back
to J. Tuzo Wilson, who thought the Great Glen fault
of Scotland connected with the Cabot fault of North America. Later, Harland wanted to include the Billefjorden fault zone of Spitzbergen,
Norway, as well, making this one whopping big transform. Eventually, the Cabot was no longer considered
to be a transform fault. Harland said
the Billefjorden "transform" had moved 1000
km sometime after the Devonian, but before the Carboniferous, and was left
lateral. LaMar
had his doubts, and besides, Norway has such spectacular scenery, why not find
out for himself? Operating between a
field hut the size of a piano box, and a combination beer hall and restaurant
for which a sign was not necessary, LaMar and his
Zip-A-Dip cohorts mapped relentlessly.
Dodging glaciers, visiting Russians, and an apparently endless supply of
Zip-A-Dip field equipment strewn about, they determined Harland's transform was
actually a reverse fault with the Heckla Hoek Gneiss riding up over the Devonian Old Red Sandstone,
all unconformably overlain by the Carboniferous. So the whopping big transform came unzipped,
dropping the Billefjorden fault along with the Cabot,
leaving only the Great Glen fault as the sole surviving transform. So in the words of yet another great
commercial enterprise, "Why Zip, Zip, Zip, when one Zip'll
do ya?"
Questions by Gene Robertson, E-an Zen, a blue shirt, and LaMar, himself, who wondered why nobody had asked about paleomagnetism, and then told us all about it.
President
Fiske announced the program for the next meeting to the 73 in attendance, and adjourned
us at 9:56 PM.
THE
GEOLOGICAL SOCIETY OF WASHINGTON
1164TH
MEETING
April 8,
1987
The 1164th
meeting of the Society was called to order by President Fiske at 8:02 PM, and
true to form, the gallery of geologists and other assorted gurus weaned itself
from the beer table with surprising alacrity, and was seated in one minute
flat. The minutes of the previous
meeting were read and corrected. Four
visitors were present and duly applauded:
Charlie Prewitt, Director of the Geophysical Laboratory; Johann Gieb, University of Marburg; and a set of bilateral Gregs from Johns Hopkins, one Dipple
and a Sims. President Fiske announced
the council's progress in resolving the chronic condition of late, errant, and
otherwise missing meeting notices that are seemingly sucked into another
dimension.
On the fun
side, James Clarke invited us on a field trip to Calvert Cliffs to be held
Saturday, May 9, promising something for everyone - you know, things like heavy
minerals, migration of fluids, weathering phenomena, shoreline processes - the
usual fare of GSW's program agenda. Tom Dutro protested vigorously that fossils
are the REAL reason people to Calvert Cliffs, which seemed to catch Mr. Clarke
by surprise. Apparently paleontologists
are more of an endangered species than we thought!
In an
informal communication, Daniel Milton told us about some strange goings on in
the plagioclase feldspars from a dismembered mélange in the Appalachians. Dan saw a calcic plagioclase rimmed with a
more sodic one, along with some discrete crystals of sodic feldspar. Examination by SEM confirmed all this,
leading Milton to believe there were at least two, maybe three plagioclases
present. Dan said he didn't know what
led to the wild and crazy array of plagioclases, or, for that matter, if the
rocks were the result of prograde or retrograde
metamorphism. If anyone can give any evidence
these are NOT phases in equilibrium, he'd like to hear from you. Operators are manning the switchboards now -
that's 1-800-GEO-HELP.
For the
first formal talk of the evening, Dan Hayba presented
"Fluid inclusion evidence for hydrologic and hydrothermal processes in the
Creede mineralizing system, Colorado." With over 2500 observations under his belt, Hayba was loaded to the hilt with data. If you really want to concentrate a sodium
solution, he says, BOIL the
stuff until it steams. That usually
happens at depth, perhaps lending a new dimension to the term, briny deep. If the roof leaks and snowmelt at 0ºC drips
through, one can always be thankful for the increased possibility of shallow
mixing. Pressing the fluid inclusion
data for all 2500 observations into service, Hayba
produced an elegant model for the paleohydrology of
the Creede District.
By tweaking ore bodies with such romantic names as the Bulldog Vein,
Southern Amethyst Vein, OH Vein, Midwest Vein, and Northern Amethyst Vein, Hayba determined the Creede
system was fed by two different sources, one from the north and the other from
the south, with deep mixing between the two.
Now it's difficult to see now he could get such magnificent results,
when all his observations were in vein.
Questions by Bob Tilling, Dave Stewart, Phil Bethke,
E-an Zen (twice), and Phil Candela. Paul
Barton answered Candela's question before Hayba could
do it himself, which prompted our speaker to tell Martin, "I'm glad you
came!"
John Valley
presented, "The role of fluids in crustal
metamorphism," the second talk of the evening. If you like fluids in ore veins, you'll love
fluids in the deep crust, where rocks can get from amphibolite facies to granulite with the
greatest of ease. The problem is we
don't always know just exactly how the rocks did it. Our speaker reminded us that the traditional
ways consider the activity of water with respect to pressure and
temperature. We should also remember that
fluids can mean flooding, and there are those who like the idea of swamping the
deep crust with either methane or CO2, as well. Trying to decide
which of these scenarios has happened is tricky to decipher, because the fluid
inclusions by themselves are misleading, as Valley says they form after the
peak of metamorphism. In the
Adirondacks, for example, he told us that calcite in veins resulted from healed
planes of CO2-rich fluid inclusions, and they indicate a brittle,
post-metamorphic event. Clustered near
the calcite veins are fluid inclusions which contain mixed water and CO2,
and our speaker says all this indicates the inclusions are telling us not
about the peak of metamorphism, but rather about the path of
uplift. Furthermore, there is no
evidence for a pervasive CO2 flooding event. Thank goodness! Having your basement flooded with either
water or swamp gas is bad enough, but Lawrence Welk
bubbles, too? Questions by Eileen McLellan, Sorena Sorensen, Paul Lohman,
Doug Rumble, Moto Sato, E-an Zen, Dave Stewart, and
James Clarke.
Tom Jordan
finished up the evening with his talk, "Are there continents on the
core-mantle boundary?" Noting that
the program was taking us deeper and deeper into the earth,
Jordan presented a model of how he thinks our planet might be working. Armed with a whole heap of seismic data, he
figured the behavior of seismic waves could be explained by a boundary layer of
either a chemical or thermal nature at the core-mantle interface. This is just what we do with respect to the
continents, Jordan says, hence the title of his talk. Any heterogeneity at the core-mantle
interface can be explained by complications either above the boundary, below
the boundary, or at the boundary, itself.
As to what this stuff may be, or exactly where it is, nobody knows, but
it could be something like either the dregs of a subduction zone, or primary
chemical layering left over from the origin of the earth. In response to a question from Doug Rumble,
Jordan replied, "Don't believe anything a seismologist tells you, but you
can rely on me! Now I ask you, would you
buy a used seismometer from this guy?
Some heavy grilling by Robin Brett, Sorena Sorensen, Gene Robertson,
Dave Stewart, and E-an Zen.
President
Fiske announced the program for the next meeting to the 118 101 in attendance,
and adjourned us at 10:0l PM.
THE
GEOLOGICAL SOCIETY OF WASHINGTON
1165TH
MEETING
April 22,
1987
The 1165th
meeting of the Society was called to order by the President Fiske at 8:00
PM. The minutes of the previous meeting
were read, and corrected, as usual. Tom
Dutro raised a particularly picky point of order about how the Secretary
arrived at the attendance figures.
That's OK, Tom, no hard feelings - I've even arranged for an escort
service to your car tonight. They're the
two guys from Jersey. Two visitors were
introduced: Rebecca Bedell,
an art historian, and Linda Riddle. The
names of four newly elected members were announced: Miriam Baltuck,
Charles Prewitt, Roger Peebles, and Charles Druitt. President Fiske, sounding just like his
predecessor, Robin Brett, asked if everybody had paid his dues. Upon hearing awkward mumblings from the
gallery, he then shifted the subject to meeting notices, and announced the
whole bundle for the USGS at Reston , featuring the bill of fare for the
night's meeting, was lost. The mumblings
escalated to audible anxiety, and sparked a lively discussion. Not to worry.
Careful analysis of our cost/benefit ratio with respect to meeting
notices by Richard Tollo, our Treasurer, has led the
GSW Council to change our contract for printing and distribution from JAW
Computer Services, to the Mineralogical Society of America. Our Council tells us this is the definitive
stroke against the dreaded dragon of delinquent meeting notices. Watch this space. On behalf of James Clarke, Kathleen Krafft announced the Spring Field Trip to Calvert Cliffs
was being led by Lucy McCartan and Buck Ward on May
9.
Rebecca Bedell, introduced to the Society only moments ago, gave
the first of two informal communications about her detective work on 13 paintings
done in the mid-19th century by artists of the Hudson Valley school. All 13 were praised by critics, but, are
these paintings scientifically accurate, and, in fact, can we tell what place
each one represents? Being a captive
audience, we aided our scholarly sleuth in typical GSW fashion - we jammed one
of her slides in the projector, and stuck another one in sideways; providing an unusual example of vertical
bedding and horizontal trees defying gravity at some intriguing place in New
England, now lost to science, but captured for posterity by a crackerjack
artist. Bruce Hanshaw
concluded the informal communications with a short spiel about the oldest
scientific congress in the world. In fact, the only congress that spawned a
union. No, this wasn't a provocative
remark about Strom Thurmond, it was a plug for the 28th International Geological
Congress to be held Washington, D. C., July 9-19, 1989. Hanshaw says there
will be 150 field trips, including Antarctica, and pleaded for local Geohosts, that is, a volunteer to help someone from a third
world nation to register, as well as providing said registree
with bed and breakfast.
For the
first formal talk of the evening, Jeff Grossman presented, "That which
survives: Relicts of the early solar
nebula in chondrites." Grossman
says the ordinary chondrites are primitive rocks, chemically. Spherical particles known as chondrules make
up 75% of an ordinary chondrite; the other 25% is a dark matrix that
surrounds the chondrules. Ordinary
chondrites are not only primitive, they are very ancient. All of them seem to be 4.5 BY old, and all
were formed at the beginning of the solar system, and therefore define this
blessed event. The individual chondrules
took their own sweet time to form, however, and most of them needed another one
million years to do the job. Grossman
made a convincing argument that the chondrules are remelted dust from the
earliest epoch of the solar system, and a whole bunch of energy was necessary
to do this melting. In answer to a question
by Ben Burton, we found out that the compositions of chondrules and matrix are
different, but taken together they represent the composition of the sun. I wonder if that means the chondrules and
matrix got that wallop of energy from a punch in the solar plexus. Further questions by James Galvin, Moto Sato, and E-an Zen.
The second
talk of the evening, "Crustal units in the
western United States: Magnetic and gravity evidence," was given by Peter Johnson. Showing us a jazzy slide of a many-splendored, magic Technicolor new map to be published in a
few month's time, Johnson had his hands full telling us what all the colors
meant. Magnetic stripes never
lie, and along the Juan de Fuca spreading center, the Pacific plate side is
spreading faster than the other side, where the Juan de Fuca plate is taking it
relatively easy. On land, the exciting
things are a couple of accreted terranes, one of seamounts, and the other of
Mesozoic rocks. Unfortunately, the
magnetic stripes mysteriously vanish from the accreted terrane where the top of
the downgoing slab disappears down the subduction
zone. This adds to the Technicolor, but
wipes out the barcode, so Johnson may have to resort to GROUND TRUTH in order
to sort things out. He thinks some
spreading centers were patchily covered by sediments which were then affected
by low temperature metamorphism. If this
is true, Johnson believes the low temperature metamorphism would obliterate the
magnetic minerals. Mebbe
so, mebbe so, but to find out he has to look at the
eastern edge of the accretionary province in Oregon
right where the Cascades are piled on top of it. Lotsa luck,
Peter. Questions by Tilling.
Richard Luth finished up the evening with his talk, "Effects
of fluorine on phase equilibria and liquid structure
in silicate systems." Why
fluorine?, he asked, and so did I - this was the second fluorine talk this
year. Luth
explained by telling us that fluorine is a significant component in some
igneous rocks, and the interactions of fluorine with magmatic
liquid provides insight into the structure and thermodynamics of the
liquid. Previous workers have looked at
topaz and rhyolites, but Luth
likes a diopside-depolymerized system because he can
then compare the effects of fluorine with those of water. Sure enough, fluorine and water are a winning
combination once again! Luth found that in systems lacking aluminum tetrahedral
coordination, fluorine will polymerize the liquid by complexing
the network-modifying cations. And in systems with aluminum, fluorine may
either polymerize or depolymerize the liquid,
depending on the relative stabilities of the complexes of fluorine with respect
to cations involved in charge balancing, network
forming, and network modifying.
Questions by Moto Sato and Benjamin Burton.
President
Fiske concluded the evening by stating, quote, "We will by golly get the
notices for our September 30 meeting out to you all," unquote. I DIDN'T GET MINE YET! NEITHER DID HE! The 74 in attendance were then adjourned, but
don't ask me what time that was - I was too busy recounting the house so Dutro
wouldn't pester me again.
THE
GEOLOGICAL SOCIETY OF WASHINGTON
1166TH
MEETING
September
30, 1987
The 1166th
meeting of the Society was called to order by a smoldering, sputtering, and
fuming President Fiske at 8:19 PM. The
Cosmos Club, our twice-monthly host, landlord, and otherwise ambivalent ally,
had sandbagged the start of the first Fall meeting by providing us with a slide
projector from Toys 'R Us, but no lens.
It turns out that J. Thomas Dutro, Jr., that pesky past president who enjoys
poking fun at the podium from the safe haven of the audience, was elsewhere in
the building giving his OWN slide talk
on the Grand Canyon, and he had the only decent projector the
Cosmos Club owns. As luck would have it,
this peripatetic paleontologist provided tonight's program for the Society, one
sure way for us to get a lock on the Cosmos Club's spartan
stable of audio-visual equipment. If you
can't beat 'em, join 'em. We all know that John Wesley Powell was one
of the co-conspirators who helped conceive the Cosmos Club - who could miss his
bust outside the door to this very auditorium?
I learned that in its early days, the Cosmos Club was nurtured at the
bosom of Dolly Madison's house on Lafayette Square. The Club cashed in when the President's Park
became the focus of urban renewal for the new U. S. Court of Claims building. The Club took the loot from selling Dolly's
house to buy these magnificent digs, but apparently, out of some quirk of their
ritual known only to them, they kept their museum-quality projector! After all, if it was good enough for Powell,
it ought to be good enough for us!
Apologies for the delayed start were extended to all by President Fiske,
with the promise that one tardy beginning was one too many, and the Cosmos Club
would be hearing plenty from him about their poor showing. Staunch patrons of the beer buggy somehow
seemed not to notice anything was amiss during their extra minutes of Miller
Time.
The minutes
were read, and as long as Dutro was occupied elsewhere, and nobody else could remember
what had happened five months ago at our last meeting on April 22, the
secretary's report was accepted as read.
Three guests
were introduced: Alexy
Marchenko, from the Leningrad Mining Institute, and
currently visiting professor in The Geology Department at George Washington
University; Vladislav Ryaboy;
and Jim Webster. Five new members were
introduced: M. Sheila Marshall, Frank H.
Jacobeen, Jr., Daniel Waltz, Brian E. Orlick, and Bruce Nelson.
President
Fiske announced the death of Lloyd Henbest, and the
membership stood for a moment of silence in his memory. A second announcement was about the new system
of meeting notice distribution by the Mineralogical Society of America. Apparently a few of us, including about 20 in
the audience, GSW's President, and yours truly, have
fallen through the cracks. Please let us
know if you've been missed, and we'll do our best to straighten it out. Gene Robertson announced the nominating
committee's slate of officers for the next term, to begin in December.
For the
first formal talk of the evening, Bevan French presented, "Vredefort Bronzite Granophyre: Chemical
Evidence for Origin of an Impact Melt."
French began by telling us the Vredefort
structure was unique and controversial, and that it would probably remain
controversial after his talk. The Vredefort structure has a large, circular core of granites,
2.5 BY old, surrounded by a section of sediments and lavas, long-known to be
characterized by upturning, overturning, and fracturing - and more recently, by
shock features of metamorphism. The
question is whether the Vredefort structure with its
granite core was formed by external causes, namely by a deep-seated impact of
an extraterrestrial object, or by intrusion of a large body of magma which
bulged up an asymmetrical mushroom-like structure. It's sort of like asking what the crocodile
has for dinner. The youngest granite in
the core of the Vredefort structure is the bronzite granophyre of the title,
and it is the only unit not cut by pseudotachylite,
so it is a key player in this saga. The
concept of an impact melt has going for it the generation of intense shock
waves, pressures of several megabars, and
temperatures of several thousand degrees centigrade. After impact, the melt would move downward
and spread out like a liner inside the impact crater. The bronzite granophyre, Oh Best Beloved, forms some nifty long dikes
with cooling rims, not inconsistent with an impact melt. To look at the other option, namely a whomping big intrusion of granitic magma acting like a
gigantic punch from below, we need to examine what would happen during
assimilation of the wall rock, namely basalt, shale, and quartzite, by the
parent magma, to see if that would give us the bronzite
granophyre, as well.
French designed a computer program that takes a series of ingredients
and compares them to the final product to see which model works better. So what does the crocodile have for
dinner? It turns out the assimilation
model doesn't explain the bronzite granophyre at all well, but the impact model can produce it
with no sweat. Questions by Mike
Phillips, George Helz, Mike Ryan, Roger Nielsen, E-an Zen, Phil Greenly, Pete
Toulmin, and Ralph Haugerud.
The second
talk of the evening, "1982-84 Volcano-Seismic Crisis at Campi Flegrei, Bay of Naples,
Italy," was given by Robert Scandone. Campi Flegrei is an area west of the Bay of Naples, which has
experienced a lot of recent volcanism, beginning about one MY ago. It is aptly named, as Campi
Flegrei means "Burning Fields." In a magnificent satellite photo we saw a
breathtaking sweep from the Bay of Naples to the Isle of Capri, an area
surrounded by an enormous caldera that has subsided to the tune of 3 km since
the Plio-Pleistocene, and a vista dotted with gobs of
volcanoes. The only disquieting
intrusion into our reverie from space is that 3 million people live there. Measurements of the land movements have been
made since 1800, with wonderful instruments like mollusk-bored marble columns
on Roman ruins exposed at maximum uplift, serving as a talisman of some high
times - dry ones, too. In 1983 the
uplift reached crisis proportions from Naples to the west coast. Pozzuoli was smack in the middle of the
seismic activity, and experienced the maximum uplift - most people bit the
bullet and moved away. The records since
1900 show there was a long interval of subsidence from 1905-1922, followed by
the short, intense uplift of 1982-85.
The subsidence and uplift mirror each other, and always act in the same
area. Scandone
believes we are dealing with an area collapsed by several episodes of volcanic
activity, which is uplifted again by an increase in pressure. Ben Burton asked if there was a big magma
chamber beneath the Bay of Naples that was the culprit, and Scandone
replied, "That's the big question."
Other questions by Moto Sato, Doug Rankin, and
Tom Simkin.
Richard
Carlson finished up the evening with his talk, "Crustal
Growth on the Oregon Plateau." The
Columbia Plateau, with its 3000-4000 feet of classic continental flood basalts,
stands in contrast with the rocks of the Oregon Plateau, part of the Basin and
Range Province. The rocks of the Oregon
Plateau are bimodal in composition, with both basalt and rhyolite
present, and they occur in two phases, fractionated, and relatively unfractionated. Just
how did this come to be? Carlson used reconnaissance
sampling of young basalt flows, K-Ar dates, and
geochemical isotope studies to help sort it all out. The trend of older basalt to younger rhyolite from west to east led him to think the Juan de
Fuca Ridge didn't like continents, so it went west, dragging the subduction zone
with it. Before about 18 MY ago, the
basalts were arc-related volcanics, but after 18 MY they were extensional, and
thinning of the crust about 15-17 MY ago let the flood basalts through. About 10 MY ago the proto-Oregon Plateau
opened up, characterized by some high-aluminum basalts from a nearly successful
rift. This scenario, along with some
selected tender bits of mantle components to melt up and throw in the
subterranean stew from time to time, gave Carlson everything he needed at just
exactly the right place, and just when he needed it. Questions by Eileen McLellan,
Greg Harrity, E-an Zen, and Bill Haughn.
President
Fiske announced the program for the next meeting to the 86 in attendance, and adjourned
us at 10:06 PM.
THE
GEOLOGICAL SOCIETY OF WASHINGTON
1167TH
MEETING
October 21,
1987
The 1167th
meeting of the Society was opened by President Fiske at 8:00 PM, with the
announcement that this was a special occasion, a concurrent meeting with the Paleontological Society of Washington, otherwise known as
PSW. President Fiske introduced the
President of PSW, Richard Grant, who was asked to call the meeting to
order. Grant complied obligingly, and
extended an invitation for all to come to the next regular meeting of PSW on
November 18 at the National Museum of Natural History.
The minutes
were read and approved. Seven visitors
were introduced: Cherrie Oaks, Arthur
Cohen, Jason Warner, Linda Welzenbach, Mark Govan, Carol Russel, and Laura
Wilbur. Practically all are students
from the University of Maryland, an obvious sign that Peter Stifel's
sabbatical year has ended. Welcome back,
Peter, and warmest greetings to all you Marylanders.
For the
first formal talk of the evening, John Pojeta, known
to some as John Pojeeta, and others as Juan Pohayda, presented "Ascaulocardium
armatum (Late Cretaceous) -the ultimate
variation on the bivalve paradigm."
Pohayda says a paradigm is fancy word meaning
"example," and Ascaulocardium is a
pretty fancy clam, albeit a weird one.
Some commercial fossil dealers collected this thing that looked like
twisted calcified spaghetti from Coon Creek, Tennessee, along with gobs of
Cretaceous mollusks, for which the locality is famous. After elaborately preparing this odd jumble of
bent plumbing made of calcite, they brought it to Norm Sohl
to find out what they had. It turned out
to be an uncanny clam, well outside the ordinary range of pelecypod
shell architecture, which Pohayda and Sohl dubbed Ascaulocardium
armatum, meaning "the bag-piper's
heart." Its living relatives, the clavagellid clams, live in the clear, shallow seas of
subtropical to tropical shelf areas, whereas the bag-piper's heart is known
only from Upper Cretaceous rocks of the Gulf and Atlantic coastal plains, and
probably lived in cooler water. Living clavagellid clams are popularly known as the "watering
pot," or "salt and pepper shaker" shells. That's because at the end of a calcareous
tube there is a bulbous calcareous plate, perforated by a series of pores, or
tubules, more or less similar to the spout of a gardener's watering can. The whole affair looks remarkably like a
marital aid that not even a Parisian purveyor of paraphernalia promising
passionate pastimes would dare to display publicly. So much so, in fact, that one species was
named Brechites penis by none other
that Jean Pierre Baptiste Lamarck, that risque French evolutionist of the 18th century who promoted
the inheritance of acquired characteristics.
As if to show he was no sexist, Lamarck married four times, and named a
second clavagellid clam Brechites
vaginiferous!
By whatever name, these thoroughly modern clavagellid
clams burrow, living vertically in a tube with the spout end down. Burrowing is rapid and efficient, achieved by
pumping water down and out the spout, with complete burial attained in only a
few seconds. What has this to do with
its Cretaceous relative, the bag-piper's heart?
Juan Pohayda told us the four long tubes at
the front end, the triple junction of tubes coiled around the central crypt,
and the crown of tubes at the back end were all structures for hydraulic
burrowing and deposit feeding. So if the
paradigm for this pelecypod stirred your prurient
interests, remember, clavagellid clams really carried
inside plumbing to an artform, and back outside
again, information only GSW and PSW are privy to.
So, one
paradigm may really be the price for a private booth at our buddy Lamarcks's pay twalay. Blame it on inflation. Buddy, can you spare a paradigm? Questions by Phelps Freeborn, John Repetski, E-an Zen, Gene Robertson, Peter Stifel, and Jack
Frost.
The second
talk of the evening, "Conodont alteration in
regional and contact metamorphic regimes, or How the world burns," was
given by Anita Harris. You remember
Anita, she cooks conodonts to see what happens to
these extinct beasts after a few thousand hours at 300 degrees C or so. Harris is one of those old-fashioned girls
who bakes in a traditional oven, shunning new-fangled devices like microwaves. Besides, the search for new conodont recipes takes her to romantic and exotic places
like Alaska, Mexico, the Blue Ridge, the Snake River Plain, and
Massachusetts. Short-order counter
connoisseurs of conodont cuisine will remember the
runaway success of Professional Paper 995, "Conodont
Color Alteration - an index to organic metamorphism." In this classic paper of a decade ago,
Epstein, Epstein, and Harris substantiated conodont
color alteration indices, or CAI, in the range of 50 to 300 degrees C, namely
CAI 1 through 5. Recently, Vivian Rejebian, in collaboration with Harris and Steve Huebner,
turned up the wick to see what would happen to these babies at temperatures
above 300°C, especially if some water-laden methane was tossed into the
oven. The experimentally altered conodonts are similar in texture to the naturally altered
specimens from contact metamorphic rocks, but the experimental conodonts are much better preserved than the mangled, corroded,
deformed, and fractured ones from regionally metamorphosed rock. Tossing in a water and methane-rich mixture
at 1/2 kbar shows first, that color alteration of conodonts is considerably retarded by wet swamp gas, and
second, these fossils have CAI values and textures most like conodonts from hydrothermally
altered or contact metamorphic rocks.
Therefore, CAI values of 6 to 8 cannot be used to assess temperatures of
hydrothermally altered rocks, but they can be used as
a valuable tool for targeting potential mineral deposits. Though these wondrous little beasts may be
the paleontological saviors of many metamorphic
geologists, super-heated, super-squeezed conodonts
usually self-destruct somewhere beyond chlorite grade in regionally
metamorphosed rocks, or 600°C in contact metamorphic rocks. To quote Harris, "Conodonts
are a joy to behold, but not necessarily geologically forever." Questions by Moto
Sato, E-an Zen, Marcus Key, and Sorena Sorensen.
Bruce Wardlaw finished up the evening with his talk,
"Paleontology and geology of nuclear craters at Enewetak: Results from project PEACE." Starting off with a slide of a swollen,
scarlet, steamy, mushroom-shaped nuclear cloud (hardly a peaceful symbol,
except perhaps in the minds of the current administration), Wardlaw
asked, "What does paleontology have to do with these Big Boys?" It turns out that paleontology solved a big
question in the minds of the Big Boys at the Pentagon, namely, what is the
etiology of nuclear craters produced by megaton nuclear blasts? The only places to look were Enewetak and Bikini - the only places where megaton nuclear
devices were ever detonated under controlled field conditions. Enewetak was lucky,
it got two. One, named KOA, produced a
crater on the island, and the other, OAK crater, was in the lagoon under 14
feet of water. Models from the Big Boys
at Defense predicted the craters would deep and narrow, but they turned out to
be wide and shallow, instead. How
come? By comparing the stratigraphy of
the craters with the biostratigraphy of an
undisturbed section, these peaceful, patient paleontologists detected piping of
sand from 600 feet down that wound up as sand volcanoes on the terraces of OAK
crater. This piping, combined with
lateral flow at depth, greatly thinned the faunal zones beneath the crater in a
systematic way. In addition, our
Peacenik paleontologists mapped the rubble flowstone that formed when the
crater rebounded. And a nice touch was
their correlation of the deposits formed by the collapse of the ejecta flap, otherwise known as the "slap of the
flap."
Marcus Key
asked why Casper Weinberger cared so much about these craters that he was
willing to fund a megabuck study of these megaton military pits? Wardlaw replied
that Defense was more than passingly curious about
the effects of a big blast on missile silos, for one thing, and the Survey's
paragons of paleontological prowess were able to
deliver on all counts. May the FORCE be
with you.
President
Fiske announced the program for the next meeting to the 84 in attendance, and adjourned
us at 9:47 PM.
THE GEOLOGICAL SOCIETY OF WASHINGTON
1168th Meeting, November 11, 1987.
Canceled due to snowstorm.
MINUTES OF THE GEOLOGICAL SOCIETY OF
WASHINGTON
1169th Meeting: December 2, 1987
President Fiske called
124 members of the Society to order for the 1169th meeting at 8:05 PM. The
minutes of the 1167th meeting were called for,
read, and approved. Robin Brett inquired about the minutes of
the 1168th meeting. President Fiske
informed Brett that a blizzard on the 11th of November had cancelled that
meeting. Brett asked why the Society had
counted a meeting that had not occurred.
Fiske replied "Because a program announcement had been
distributed."
Guests G. Ron Spencer and Catharine Toulmin were
introduced. Newly elected members Deborah R. Jerez, K. Michael Cline, Michael
D. Cavanaugh, Sara Arav,
Margaret Kasim and Albert Y. Sun were
introduced. President Fiske announced
the death of Quentin Singewald and George Schoechle. A moment
of silence was observed.
There were no other
announcements, informal communications
or old or new business. President-elect
Douglas Rumble introduced the speaker,
outgoing President Fick Diske
[correction: Richard Fiske, by Douglas Rumble], and complimented the wine
served at the Cosmos Club.
President Fiske's
address was entitled "Two Worlds of Explosive Volcanism." The title refers to subaerial
and submarine eruptions. The talk was a
progress report of ongoing research into how volcanic detritus erupted below
the ocean's surface is deposited. The
locally fossiliferous volcanic rocks of the Shirahama
Formation of the Izu Peninsula in Japan illustrate
that submarine pyroclastic rocks deposited near vents
lack fine volcanic ash and contain pumice clasts about ten times the size of
the largest lithic clast. Theory and
experiments suggest that such deposits represent a group of sedimentary
particles with a similar terminal velocity in seawater. Thus, submarine volcanic deposits that look
poorly-sorted by size may be well-sorted with respect to terminal
velocity. Pumice erupted under water
may be denser than pumice erupted into air,
because the hot gas in erupted pumice is replaced by seawater as pumice
cools under water. Large pumice blocks
may float, partially degas and then sink when they become saturated with
seawater. Fiske has measured the terminal velocities and densities of a large
number of volcanic particles, and is planning to conduct experiments with his Device
for Attenuation of Freefalling Tephra on particles
collected from the volcanic rocks of the Izu
Peninsula.
No questions were asked.
The meeting adjourned at 9:22 PM.
Respectfully submitted,
[signed Sorena Svea Sorensen]
Based on notes of R. Rye
MINUTES OF THE 95TH ANNUAL MEETING
GEOLOGICAL SOCIETY OF WASHINGTON
December 2, 1987
President Fiske convened the 95th Annual
Meeting at 9:42 PM in the John Wesley Powell Auditorium by hauling out the
traditional Budweiser gavel. Earlier in
the evening he had opened the ll69th regular meeting and neatly dispatched
Robin Brett's question about why THAT ONE was the 1169th, when there had
been no 1168th meeting. You will
remember we had an incredible Veteran's Day surprise blizzard on the meeting
date, November 11, with some motorists stuck on the Wilson Bridge for more than
20 hours. Besides his outstanding
presidential address, Fiske's parrying with Brett over why the invisible 1168th
meeting had been sucked into another dimension may have been his finest moment
of the evening. But more about that
later.
Margo Kingston, the council secretary for
1987, read the minutes of the 94th Annual Meeting, which were approved. Next, the report of the Meetings Secretary,
yours truly, was read and approved. Aannnnnd, back to Margo again with the Council Secretary's
report. The 1987 council will be
remembered as the bunch who dragged the Society firmly into the computer age by
handing over our business operation to the Mineralogical Society of America
Business Office. And, they ended the era
of our being an outfit with no fixed address.
That is, until remodeling at the Cosmos Club in the fall of 1988 evicted
the Society and put us on the streets again.
Treasurer Richard Tollo
brought us Season's Greetings with the good news that the Society's finances
are still hanging in there. In fact, we
have a modest increase in our bank balance.
Tollo inherited a scenario in which we had
doubled the dues, RIFFED some meetings, and farmed out the business operation
to the private sector. Sort of a
cottage-craft prototype of a flexible freeze.
The Society expressed its thanks to Treasurer Tollo
for his outstanding work in establishing GSW on a firm financial footing.
At this point it became evident we should
have an auditor's report, but this tradition had somehow escaped President
Fiske's notice. He took full
responsibility for the oversight, and promised to have somebody else, namely Dan
Appleman, do the audit in time for a report at the next meeting.
Warren Wood, Membership Chairman, reported
his disappointment that only sixteen new members joined the Society during the
year. Apparently there is a perception
that GSW is an elitist group, and some people are reluctant to attend UNLESS specifically invited. As half the audience was wearing field boots,
many in attendance were dumbfounded at the prospect of being considered
elitist. We need to work on our image,
folks.
Then Leanne Milton, Public Service
Committee Chair, winged a report from memory on a marathon of activities. One colleague had yet to return the (quote)
"official black GSW science fair judging briefcase" (unquote) that
contained all her data. In the spring,
nineteen GSW members judged ten science fairs in five different political
jurisdictions. Also in the spring, GSW
shared a booth at the National Science Teachers Conference with George Mason
University and the Association of Women Geologists. It must have been a snug fit in that booth -
a sight that the 249 earth science teachers who stopped by may not have been
able to resist. Leanne personally
conducted four workshops on "How to prepare an earth science project for
your science fair" to 111 participants.
Add to this a dinosaur bone loan program to pre-schoolers,
and these are just the highlights. The Society gave a hearty round of applause
for this committee's outstanding contribution to public service. Then, just in time for Leanne's concluding
remarks, a red-faced Phelps Freeborn returned the lost "official judging
briefcase."
Now it was time for the best paper
awards. President Fiske gathered his
courage and confessed he hadn't retrieved the coveted silver bowl from last
year's winner. Even though Fiske bared
his soul in front of us, this learned Society with a reputation for being
elitist hissed him soundly. READ THEIR LIPS.
Best Paper Awards Chairman Josh Tracey
began by telling us that of the 29 regular talks and ten informal
communications, every paper had at least one table that couldn't be read from
the middle of the room. But the overall
quality of the talks was tops, making the committee's job tough, indeed. Chairman Tracey presented the Great Dane
award to Ralph Haugerud for his informal
communication about using the SEM to determine extraneous sources for argon in
samples that were difficult or impossible to date by potassium-argon
methods. As this was an idea that came
to Ralph only ten days earlier, the committee applauded him for having the guts to bring a new, barely
tested idea to the Society and presenting it so clearly. Then came the Bradley awards. Second prize went to Bevan French and Roger
Nielsen for their talk, "Vredefort bronzite granophyre; chemical
evidence for an impact melt." The
silver bowl and first prize went to Jeffrey Post and David Bish
for their paper, "Manganese oxide minerals: some new insight from powder
x-ray diffraction." As one
paleontologist remarked, "He even made todorokite
sound interesting!"
Putting on his third hat of the evening,
yours truly represented the Sleeping Bear Committee, bestowers
of our Society's highest accolade. The
other committee members, Dan Appleman and Dick Fiske, made some outrageous ploys
for the award themselves, but of course they were ineligible. In 1987 the Society did not lack for
memorable quips, some planned, some spontaneous,
but
"for the body of his work," the Bear and cup went to Dave
Stewart. In accepting, now three-time winner
Stewart confessed, "I've said if I ever got this cup again, I'll
retire!" Promises, promises.
President Fiske then thanked program
chairman Glenn MacPherson for a good year. The slate of officers for 1988 was accepted
by acclamation, and newly elected President Rumble adjourned the meeting at
10:42 PM.
Respectfully submitted,
Raymond T. Rye