GEOLOGY 1Lab Assignment Part 2

Melinda WhitemanFall 2010

Waterman Point Fault Scarp

While the Seattle area has many faults, there are few places where one can actually see them at the surface. I want to thank the Earth and Sciences department of the University of Washington for helping to point me in the right direction to finding one (it was the last thing I needed and I was starting to stress about it!) The Waterman Point fault scarp, near Port Orchard, WA, is from a reverse fault, where the hanging wall moves higher than the footwall. It has since been a bit eroded, but is still quite a sight – I never would have known it was from an earthquake fault prior to this class. The scarp is supposed to extend east, though you can’t see it due to vegetation. I can’t help but wonder if the residents know what their homes are sitting on

Mechanical Weathering -frost wedging

These pictures were taken at Rosario Beach, Deception Point State Park, WA. The metamorphic rock on this beach spends its winters in extremely cold temperatures, allowing water to get in and freeze, expand, and break the rocks apart.

In the bottom right picture, it almost looks like there is a pile of loose rocks; when I tried to pick one up I realized they’ve just been weathered that way and are still solidly attached! There was one spot where I was able to “wiggle” out a piece, which I used in Part I as one of my identifications.

Mechanical (Root) Weathering

This is a great example of root weathering of a very large boulder near Snoqualmie Falls, WA. This large tree’s roots have managed to break the rock in two. I wish I had gotten a couple wider shots, but after this was taken a minor mass wasting event occurred: the muddy slope I was standing on didn’t want me standing on it anymore! My camera went face-down in the mud and I moped my way to the restroom to clean up….

Mass Wasting & Erosion

Snoqualmie River

Mass Wasting & Erosion, continued

The preceding pictures and those on this page were taken a mile or two downstream of Snoqualmie Falls. Recent snow and melt must have oversteepened the opposite bank – quite a few rocks, a lot of mud and a few trees found their way down the slope into the river itself.

Continental Sedimentary Environment

The top two pictures are of Snoqualmie Falls; the bottom right is the Snoqualmie river downstream at Fall City, WA. Streams are a major player in continental sedimentary environments, moving and depositing the most sediment. The Falls themselves are also used for hydroelectric power, another great example of the practical use of geology.

Transitional Sedimentary Environment

Rosario Beach

Inlet in Southworth, WA, just east of Yukon Harbor

Transitional sedimentary environments are shorelines – the transition between continental and

marine environments. The sediments are mainly deposited from erosion of the land or washed in

from the ocean, though many other processes are or can be involved.

Marine Sedimentary Environment

Vashon IslandSouthworth

Marine sedimentary environments are divided into shallow (up to 200 meters) and deep (over 200 meters). These pictures were taken from a ferry on the Puget Sound, crossing from Seattle to Southworth via Vashon Island. The shallow marine environment along the borders of the continents can have a variety of sediments, including eroded land and sea life.

Practical use of Geology

Diablo Dam

Diablo Dam is part of the Skagit River Hydroelectric Project by Seattle City Light, and holds Diablo Dam which is known for its beautiful turquoise color (due to suspended particles ground away by glaciers.) The two left pictures were taken last June, before this class, and my husband and I both commented at the time that it was really neat how they used the existing rock and canyon to build it on. Unfortunately, I don’t feel that the pics I took from the road quite do it justice, so I’ve added the only picture that I didn’t take myself – the aerial. From above you can really see how smart they were when choosing to place the dam where they did!

Aerial photo credit: Copyright 2002-2010, John H. Scurlock, Photographer/Pilot http://www.pbase.com/nolock/image/75332429/original

Final Thoughts

The above picture is what I call “My First Glacier” – taken from the North Cascades National Park Visitor Center off N. Cascades Hwy 20 last June. I call it that because it was the first time I ever really saw a glacier and started to really understand what they were like. Just a few months later we started this class, and I look back and see all of this in a new, incredibly interesting way. In fact, I now look around and can’t help but think about how what I see was formed, or make exclamations like “Oh look, an arete!” or “Ooh, there’s some mass wasting!” I’m fascinated by our planet The background picture on the first slide was also taken along Hwy 20 and, while I didn’t know it at the time, is a great example of a glacier-formed valley (great curvature!) high in the Cascades.

Finally, remember: metamorphically speaking, schist happens!