Thread by @GeoBrentatlarge

1/ Wednesday in the Chehalis Valley with Carie-Ann Lau, ex grad student, now session instructor EASC 411 Terrain Analysis. This weekend students will be field checking their terrain and terrain stability map. Interesting terrain types and stratigraphy. (thread) #SFUGlacialGeology

2/ Oldest sediment in the valley are these oxidized fluvial gravels. Ages in the lowest gravel are 29 ka. Alternating gravel and lacustrine represent blockage by glaciers at the mouth of Chehalis. Wood present at ~19,000 years old.

3/ Detail of tree at contact between gravel and glaciolacustrine dated to ~19,150 years old.

4/ Lots of glacial lake sediments in the valley resulting in >100 m of sediments in some areas. Ice in the Fraser Lowland blocked the mouth of the Chehalis during both initiation of glaciation and deglaciation. Some sediment have been deformed by overriding ice.

5/ Love this advance subaqueous outwash (proximal sorted sediments deposited in a lake). Till on top. This confuses the students a bit since it is unusual, so a little difficult to write a terrain symbol for.

6/ Looks like some good old boys enjoy the subaqueous outwash as well! Nothing like shooting holes in propane tanks, plus anything else that is handy, and burning TV’s, as well as anything else that is handy. #yeehaw!

7/ Paraglacial fans (a la Church and Ryder 1972) occur immediately after deglaciation, this increased sedimentation is the result of abundant sediments and little vegetation. The fan at Boulder creek is exceptionally large and is also a road maintenance issue.

8/ Other side of valley is not as well traveled. Uncontrolled road drainage makes the road a little sketchy and fallen trees required some pruning.

9/ 4x4’in! #yeehaw!

10/ Not trip to the Chehalis is complete without a stop at the Deroche General Store for the greasy fried chicken! Don’t tell my doctor.