I've found these odd circles or spirals carved into the alpine tundra in several places, and I suspect they are the work of ground squirrels. Not sure why they are so symmetrical though. Either that, or it is the work of extraterrestrials.
Park on the little landing below Summit Lake (waypoint) and follow the trail till you near the now-capsized Black Pearl. Then head up the steep pitch, and as it tops out, work your way around to the left, curving with the base of the ridge. Start shooting for the creek you can see in the distance, crossing a few minor run-offs on the way. You'll find the cache near the "crop circle", probably where you'd expect it to be!