Rachel and I spent the weekend in the Medicine Lake Highlands (north, in the Modoc National Forest). This area is a large shield volcano: the largest volcano in the Cascades by area and volume, just not height.
We went to Glass Mountain, which is comprised of a lot of obsidian (black, shiny volcanic rocks) and pumice (gray, course volcanic rocks), which result from catastrophic volcanic eruptions and extremely fast cooling of lava. We spent some demonstrating some feats of strength with said rocks as we continue our training for the world's strongest person competition:
This is a photo looking north from Glass Mountain. In the distance is Lava Beds National Monument, Tulelake, and Oregon:
No actual pictures of Medicine Lake, where we camped. It is a big, cold lake fed by snowmelt in the main crater of the Medicine Lake Volcano.