Mount Adams rock and snow avalanche, August 1, 2008

Great picture Joe...My hunch was just based off the article linked. I haven't been down there this year but from what I can see in the photos there is even less snow up there now than possibly in that pic taken in september.

Here's a link with some pretty good pictures and info.

I think Amar has it right. It probably was at the base of the glacier since it happened before in 97. Either a rockslab at the base or hydrothermally altered rock/mud. The latter, a mud bed surface glide avalanche seems most likely.