You should answer as many of the following questions as you can in your write up. Draw sketches in your notebook at every field location of any geologic features. Remember to use a scale. Ask your instructor if you don’t understand what to do.
Overview of trip 2: This
trip will focus on coastal processes and hazards, the marine geologic rocks of
the coast (Eocene and younger age), large landslides, and evidence of tectonic
deformation. Although we will have several major stops with field activities
(listed below), we will also stop at various scenic viewpoints to observe
geologic features, landforms, natural process, and of course scenery! A pod of
Orcas was active close to shore near
We will leave the
Rest stop: Just after arriving at
Stop 1: Landslide along SR 107: At Montesano, we will take SR 107 south about 3-4 miles to the location of a recent landslide that closed the entire road Here we will observe the features of a major landslide.
Stop 2, Viewpoint and
discussion: We will stop briefly at
Continue north past Kalaloch about 7 miles to
Stop 4. Beach 4: Tides permitting, we will walk north a short distance to Starfish Point to make observations of the geology and beach processes. Upon return we will stop to look at overturned sandstone layers of the Hoh Formation where the beach trail descends to the beach..
Stop 5 Kalaloch: We will stop at the campground and walk to the beach, tide permitting.
Mileages: 5 mi from Exit 82 to 88; 46 mi from I-5 to
Field trip activities:
En route: Observe the
landscape as we drive downstream along the
B) Why are rocks of marine origin located here?
C) Notice the great width
Stop 1. SR 107 landslide: At Montesano, we will take SR 107 south about 3-4 miles to the location of a recent landslide that closed the entire road A) Draw a rough sketch of this landslide. B) What kind of landslide is it? C) Describe the nature of the rock material making up the soil nearby? D) Did geologists make any interpretations about the cause and behavior of the landslide? Landslides are one of the most costly of all geologic hazards!
B) Is there a prominent
bedrock bench visible? If so, about how high is it? C) What about the extent of
the bench—does the flat top of
Stop 4 Beach 4: A) Where the trail meets the beach, check out the bedded sediments and sketch them. These layers have been interpreted as turbidite deposits. Turbidites are the deposits of submarine landslides.
B) Examine the layers up
close to see if you tell with way might be up? Any clues? These rocks are part
of the Hoh Formation described by Welden Rau. His Bulletin 66, Geology of the
Stop 5: Kalaloch: A) Look for the wave-cut bedrock bench at the beach here—where is it? B) Describe and sketch the sediments exposed in the beach here. C) How would do you interpret the prismatic structures visible in the outcrops? D) Are you observations of the beach cobbles elsewhere similar here? E) Is there any evidence for flow direction of the currents that deposited the coarse material exposed in the beach outcrops? If so, what could be the source?
F) Discuss the possible tsunami hazards here. What are the possible sources of tsunamis? G) Where you would get information on tsunamis and maps?
Selected References and web sites
Pazzaglia, Frank J.; Thackray, Glenn D.; Brandon, Mark T.; Wegmann, Karl W.; Gosse, John; McDonald, Eric; Garcia, Antonio F.; Prothero, Don, 2003, Tectonic geomorphology and the record of Quaternary plate boundary deformation in the Olympic Mountains. IN Swanson, Terry W., editor, Western Cordillera and adjacent areas: Geological Society of America Field Guide 4, p. 37-67.
Rau, W. W., 1973, Geology of the
Rau, W. W., 1977, General geology of the southern Olympic Coast. IN Brown, E. H.; Ellis, R. C., editors, Geological excursions in the Pacific Northwest; Geological Society of America, 1977 annual meeting, Seattle: Western Washington University, p. 63-83.
Rau, W. W., 1980,
Tabor, R. W., 1975, Guide to the geology of
Olympic National Park:
Tabor, R. W.; Cady, W. M., 1978, Geologic map of the Olympic Peninsula, Washington: U.S. Geological Survey Miscellaneous Investigations Series Map I-994, 2 sheets, scale 1:125,000.
Thackray, Glenn David, 1996, Glaciation and neotectonic deformation on the western Olympic Peninsula, Washington: University of Washington Doctor of Philosophy thesis, 139 p., 2 plates.
http://geology.wr.usgs.gov/parks/olym/ [a great site based on work of Tabor and others]
http://home.comcast.net/~wa_geology/ Chris Heg’s postings of WA DGER geologic maps
http://www.wsdot.wa.gov/News/2006/01/Jan6SR107Slide.htm DOT 2006 news release re landslide