 |
||
|
|
Home
|
|
|
|
||
Meetings|
|
||
|
|
Upcoming Speakers: Previous Meetings: |
|
|
|
||
|
|
||
|
|
OCTOBER 14, 2008 MEETING
 SPEAKER: Jon Reidel (North Cascade National Park), Shrinking Glaciers in the North Cascades.
Joint meeting with NWMS.
LOCATION: Talaris Conference Center 4000 NE 41st Street;
Seattle, WA 98105; 206 268-7000. Take NE 45th St. to the
east, past the University Village (East side of
UW). Turn right (south) onto Mary Gates Memorial Drive
(five corner intersection). MGM Drive will curve east
and become NE 41st St. The Talaris entrance will be
several blocks to the east on the left (north) side of
the street. Turn left (north) onto Talaris Way and
follow the winding road to the conference center. For a
map, go to the website at www.talarisconferencecenter.com
NO HOST BAR 5:30; BUFFET 6:30; SPEAKER 7:30
DINNER RESERVATIONS: @ $30.00 for NWGS members; $35 for non-members. Send check to GINNY AGNEW 935 PINE STREET, EDMONDS, WA 98020. Telephone 425 776 6151. Ginny’s email address is agnewv@msn.com. Payment of $30 ($35 for non-members) or $10 for students in good standing at a college or university, must be received by the Thursday preceding the meeting. LATE REGISTRANTS pay $40.PEOPLE WHO CHOOSE NOT TO EAT WITH US ARE WELCOME TO ATTEND THE MEETING, BUT WE ASK A VOLUNTARY CONTRIBUTION OF $5 PER PERSON TO HELP DEFRAY THE MEETING ROOM EXPENSE.NWGS BOARD MEETING 4:30 PM at TALARIS CONFERENCE CENTER. ALL are welcome!
UPCOMING SPEAKERS:
MAY 13, 2008 MEETING
 SPEAKER: Anne Trehu, Oregon State University, Gas
Hydrates in the Cascadia Margin. Joint meeting
with AWG. Geophysical data suggest that gas hydrates are widespread in continental margin sediments, especially in accretionary complexes. However, quantification of the amount of gas present is difficult because gas hydrates are not stable at pressure and temperature conditions generally found on the Earth's surface. Recent ocean drilling cruises to central and northern Cascadia have provided key data for ground-truthing the geophysical data and for understanding the distribution and dynamics of gas hydrates formation in marine sediments. Dr. Anne Trehu is a professor of Marine Geology and Geophysics in the College of Oceanic and Atmospheric Sciences at Oregon State University in Corvallis. Educated at Princeton and MIT, Dr. Trehu has been working for more than 20 years to map plate interactions along the continental margin of western North America in order to understand its geologic evolution and the seismic hazards of the region. She has done seismic research on the San Andreas Fault, the Cascadia Subduction Zone, and the Queen Charlotte Fault, and has been involved with the SHIPS project (Seismic Hazards Investigation of Puget Sound) in northwestern Washington. She has also been involved with international research projects on the occurrence of gas hydrates, and has participated in ODP (Ocean Drilling Program) research cruises drilling into the Cascadia Subduction Zone accretionary complex.
APRIL 8, 2008 MEETING
SPEAKER: Dr. John Whitmer.
Rocky Mountain Earthquakes: Madison Canyon
[1959] & Challis [1983]
The talk was based upon personal experiences & a photographic record of repeated visits to the earthquake sites beginning within two weeks after each event. Typical of earthquakes in the Rocky Mountain Seismic Belt, these earthquakes were driven by the influence of the Yellowstone Hot Spot & the associated uplift in a parabolic pattern similar to the bow wave of a ship. Consequent extension with basin subsidence on normal faults was the mechanism for the earthquake. The Madison Canyon earthquake was notable for the immense rock avalanche which dammed the Madison River. The Challis (Borah Peak) earthquake gave rise to remarkable dewatering features. Fault scarps & associated small grabens are still visible at both earthquake sites. MARCH 11, 2008 MEETING 
SPEAKER: Steve Porter,
Professor Emeritus, University of Washington ESS, former
director of the Quaternary Research Center.
STEPHEN C. PORTER of the Quaternary Research Center, &Professor Emeritus, Department of Earth & Space Sciences, University of Washington spoke about “Late Pleistocene glaciation of the Pacific Northwest: a 40-year retrospective.” When Steve began at the UW [1962], the conventional wisdom was that the Pleistocene began about 1 Ma & there were as many as four glaciations, ending about 20 Ka. The Alpine & Lowland glaciers were assumed to have advanced simultaneously. Glacial surges were not yet recognized. These concepts were based largely on work published in 1909, without the benefit of Plate Tectonic Theory, cores of ice & marine sediment, advanced dating techniques, or consideration of the Milankovich cycle. He has worked diligently to use these tools to advance glaciology. The first ice core [1969] showed many fluctuations in extent of ice cover in the past 500 Ka. A later core extended the data back to 1.5 Ma. A subsequent core study showed 36 fluctuations. Mapping by Chamberlain [1894], Bretz [1913], Flint [1971], Crandell [eastern Puget Lowland], Easterbrook [northern Puget Lowland], Jack Armstrong & Fulton [southern B.C.], & Derek Booth [subglacial hydrology] has contributed greatly to present knowledge. Clague & Jackson [1991] identified two topographic highs in the Cordilleran Ice Sheet. It is now known that pre-last glaciation drift reached the southern edge of the Puget Lowland. Six glacial advances of the northern Puget Lobe are known. Chronology of the southern Puget Lobe is not entirely worked out. Current geochronologic data indicates that the Seattle area was ice-covered for 950 years during the last glacial advance - not sufficiently long to establish isostatic equilibrium. By 14 Ka. the ice margin had retreated to north of the Canadian border. It is estimated that the ice margin advanced 135 meters/year & retreated 500 meters/year. Porter’s work in Icicle Creek Canyon showed that the moraines are progressively older with distance upstream. Moraines dated 710 Ka. & 12.5 Ka. are thought related to climatic cooling due to astronomic impact. Insolation [i.e., the solar heat input] is the primary determinant of advance & retreat of Alpine glaciers. Sea ice extent also correlates with solar radiation intensity. Lowland glaciers do not fit this pattern. Many significant unknowns remain, e.g., the extent of ice cover between glaciations; the extent & chronology of fjord ice sheets in B.C. & Alaska; the seaward limit of ice sheets; & more detailed chronology of the Puget & Couer d’Alene lobes. Our increased understanding of regional glaciology has implications for Archeology. It is thought that there were enough ice-free refugia on the west coast of North America to permit migration along that route by boat. Migrants had reached southern South America by 13 Ka. Another hypothesis has migrants from Europe following the southern margin of the Atlantic Ice Sheet to North America. There is reason to think that some people witnessed the Lake Missoula Floods. There is no primitive society on earth that does not have a flood legend. Global warming actually began about 8 Ka. & current data indicate that insolation values are diminishing. The talk caused several people to rethink their understanding of Puget Lowland glaciation & that led to an up-tick of the learning curve. FEBRUARY 11, 2008 MEETING  SPEAKER: Dave Montgomery, University of
Washington, Dirt: The Erosion of CivilizationsJANUARY 8, 2008 MEETING  SPEAKER:
Dr. Scott Burns, Portland State University.
Terroir - Geology of
Oregon and Washington Wines.
Scott was an undergraduate at Stanford University. He
earned a PhD at Colorado University. He is renowned for
his expertise on landslides. In recent years, the
geology of wine has become his passion. He defines
terroir as the total elements of the vineyard. The
mystique of terroir in the
Pacific
Northwest is the relationship of soils to wine.
Factors making wines different from one another are the
variety of grape, geology & soils, climate, vineyard
management & the winemaker. The French, whose
classification system dates from 1866, consider terroir
more important than grape type in the production of fine
wine. Well-drained, ancient soils make good wine. Red
soil, from advanced age & weathering, is good. Many
people believe that 80% of the quality of a wine is
attributable to the vineyard & only 20% to the vintner.
Vineyard managers have learned over centuries that
drainage, color, orientation of slope, elevation &
latitude are critical for growing good wine grapes. The
vines must be stressed for that purpose. Too many
nutrients in the soil enable the vine to produce leaves
at the expense of grapes. Hot, dry conditions at the
right time are vital. There must be more than 180
frost-free days per year. The goal is to coerce vines
to produce grapes rather than leaves. The grapes must
have sugar content sufficient to produce alcohol content
no less than 12%, which is necessary to kill the yeast.
Only in recent decades have people recognized the
similarity of conditions in parts of the
Pacific
Northwest to those in the wine country of
France.
Our latitude & long, dry summers are favorable.
Southwest France, where there is no soil, & Red
Mountain, eastern Washington, with rocks & gravel for
soil, produce the best wines. In
France
& Oregon,
the bottomlands are not good for wine - too many
nutrients. In
Washington, the opposite prevails, for the
bottomland soil is derived from nutrient-poor, coarse
Lake Missoula Flood sediments. In
Oregon,
the growers farm the slopes & do not irrigate. In
Washington, they farm the bottomland & irrigate
intensely. The parent rocks of our soils are Columbia
River Basalt, Loess, marine sediments of the Coast
Range, & Lake Missoula Flood sediments. They produce a
large variety of soils. The climax of the talk was the
wine-tasting event. Participants tasted a wine from
marine sediment soil & a wine from Columbia River Basalt
soil. 27 tasters preferred the marine sediments; 11
chose the basalt. Scott’s observations have led him to
the hypothesis that if a tract of land grows abundant
poison oak, it has fine soil for a vineyard.Naturally, Scott’s talk was greatly enjoyed. I look forward to having him return to talk about landslides! DECEMBER 11, 2007 MEETING  SPEAKER:
Dr. Tom Bush, Pierce College.
"Step Aside Darwin: Geology Rules in the
Galapagos Islands."
The Galapagos Islands are well known among biologists as
well as the general public for their unique biological
communities consisting of numerous indigenous and
endemic species, including the 13 species of "Darwin's
finches". These unique islands are also well known among
geologists as an archipelago of volcanic islands
produced as a hot spot manifestation of the Galapagos
mantle plume. From an "Earth systems" perspective, where
the Earth's primary components, the geosphere,
biosphere, atmosphere, and hydrosphere interact and
influence each other, numerous large- and small-scale
examples of geospheric controls on the the development
and distribution of life in the Galapagos Islands have
occurred.
NOVEMBER 13, 2007 MEETING
 SPEAKER: Dr. Tom Pratt, USGS/UW Oceanography, Update
of- and Findings on- the East End of the Seattle Fault.
Tom devoted 7 minutes to provide information equivalent
to ”a college degree in geophysics” to prepare us to
understand the seismic sections on which his
interpretations are based. Kink bands indicate a bend
in a fault. Kink bands, fault propagation folds,
breakthrough faults, growth triangles, bedding plane
shear & deformation fronts are useful clues to tectonic
structures. The deformation front of the Seattle Fault
marks the southern end of the
Seattle
Basin. South of the deformation front, the strata dip
steeply in contrast to the flat-lying beds in the Basin
to the north. His interpretation of the data indicates
a fault propagation fold above the Seattle Fault. The
strata south of the fold crest (Newport
Hills) dip southward about 70 degrees. There is an
occasional back thrust. The
Vasa Park
Fault dips southward, with older rock thrust over the
soil. It is thought to be a splay of the main fault,
which is at a deeper level. Since Miocene strata have
not been removed, it is thought that
Vasa Park
fault motion was 500 meters or less. Estimated motion
on the main Seattle Fault is 8 to 10 km., with about 2
km. movement on the back fault. Very good data from a
profile done in the 1970’s is only recently being
analyzed. The data indicate a main fault dipping 45
degrees south, with a splay cutting to the surface.
This configuration seems to prevail across the Puget
Lowland. To the south, the Tacoma Fault dips
northward. Beneath eastern Tacoma, it breaks into
several splays. Wave-cut platforms in Hood Canal &
Henderson Bay stop abruptly to the south. A prominent
2 meter fold scarp, detectable only on LIDAR images,
marks a kink band from a growth fault active in the
Quaternary. A large magnetic anomaly north of the fold
is imputed to volcanics. South of the fold, the
anomalous unit is deeply buried. About 2 generations of
earthquakes are recorded in the sediments.
OCTOBER 13, 2007
SYMPOSIUM
The climax of the 20-year history of the NWGS was the 13 October Symposium, which succeeded beyond anything I could ever have imagined. The program was outstanding, with topics which were timely & relevant to the major issues & problems which confront our region. The location was perfect for this size of the audience (which exceeded our expectations. The organizers did their work so well that I was not aware of any significant hitch.
The quality of that Symposium leaves no doubt that the
Northwest Geological Society has a cadre of diligent,
capable people who make the organization strong. The
NWGS is a significant entity in the geologic community
of the region. Not only is it the greatest enhancement
to the quality of life in the Seattle region, but also
it is of major importance to the region. It is an honor
to be an officer in this organization.
MAY 8, 2007 MEETING |
|
|
|
||
SPEAKER: Dr.
Rowland Tabor, USGS, Living the High Life in the North
Cascades. We were honored to have ROWLAND
TABOR speak to us about “LIVING THE HIGH LIFE IN THE
NORTH CASCADES.” Rowland began his 35-year career with
the USGS in 1952 on a project with Cater & Crowder,
mapping the Holden Quadrangle. The goal was to find more
copper there. Transportation of supplies & equipment was
provided by Ray Courtney, a long-time horse-packer from
Stehekin. Rowland;s role was to hike in front of the
party, felling trees to clear a path. Helicopter use
began in 1960 & Rowland experienced a lot of “one-skid”
landings. Rowland expressed major indebtedness to Ralph
Haugerud for his part in that mapping project. Early on
they recognized three major crustal blocks & the Ross
Lake Fault. The North Cascades is comprised of
Pre-Tertiary terranes dating from 400 Ma to 100 Ma. Orogeny
occurred in the lower Cretaceous-Early Tertiary
interval. Eocene transtension gave rise to pull-apart
basins. Uplift, erosion, & glaciation shaped the
magnificent landscape. Peter Misch established the basic
framework of the Northwest Cascade System, including
rocks offset on the Straight Creek. Rowland gave a
comprehensive review of the geologist history of that
system, which consists of volcanic “arcs stacked on
arcs,” with major thrust faults, extensional fault,
magmatism, thermal metamorphism, uplift & major
glaciation. He noted that meltwater from the glaciers
had a more profound effect on that landscape than did
glacial ice. This included a major outburst flood into
the Skagit River drainage. Rowland’s work has
enlightened not only the geologic community, but the
general public & mountain climbers as well. Quite a few
people brought their treasured copies of the book by
Tabor & Crowder, “ROUTES & ROCKS IN THE NORTH CASCADES”
to be autographed.