The Camassia Natural Area in West Linn is a Nature Conservancy site, and they describe it in this way:
The rocky plateau was exposed 12,000- 19,000 years ago when the Bretz Floods poured down the present Columbia River Gorge and far into the Willamette Valley. The floods swept soil and vegetation from parts of the valley and deposited granitic boulders (called “glacial erratics”) from as far away as Canada.
It is a truly unique and sort of hidden spot, and had been recommended to me by a friend with three small children as a great place to explore. And she was right. Patrick grabbed a map and proceeded to be my trail guide (December 4th, pics).
Do you see mine and Patrick’s shadows in this picture?
You can see a sign for the 205 freeway in this picture:
Checking out seeping sap: