Saturday, March 21, 2015

Geo 1095: March 20, Day 809: Contact(s)!

There is one very distinct contact in the photo above, between what I've been referring to as the upper unit (lahar deposits), and the lower unit, which, at the time I took the photo, I was assuming were ash deposits of some kind. Turns out, they kind of are, but it's more complicated than I thought, and I only reached a satisfying conclusion a few days ago as to the nature of how they formed.

While I would describe the "upper unit" as poorly sorted overall, there do appear to be several other, though much less certain, contacts that may represent subsequent volcanic debris flows. In the annotation below, the upper-lower unit contact is a solid line, and the tentative contacts within the upper unit are dotted lines.
Photo unmodified. October 9, 2012. FlashEarth Location.

No comments: