floods of 1996, a lower portion of Boulder Creek Road was blocked by a debris flow on my first trip up there. Later in the summer, I went back, and that smaller debris flow had been cleaned up and the road reopened. However, another, much larger, flow had come down the mountainside into Boulder Creek, and utterly removed the road for something like a quarter to a third of a mile stretch. It was a couple years before that stretch was rebuilt. The boulder above, incidentally, didn't budge. The point is, it's clear this drainage can be affected by debris flows during extreme events; the stream itself has a very high gradient, and the mountainsides above it are even steeper.
And why would we want to go up that road anyway? I haven't thought to get any photos myself, but the *other* pyrite stop is in a (probable) hydrothermal explosion breccia there. Nice BB-sized to pea-sized pyritohedrons can be found easily and picked out there, though they seem less common now than in the past. Larger crystal can occasionally be found (up to a centimeter or two) but they're not common, and as a rule, have less perfect crystal form. A 360 by 360 degree "Photo Sphere," by Gary Miller, can be seen here.
Photo unaltered. July 7, 2012. FlashEarth Location.
Is This Your Hat?
2 years ago