Saturday, March 21, 2015

Geo 1095: March 19, Day 808: Miniature Badlands

"Badlands" are a type of landscape that are characterized by deep incision and densely-packed drainage paths. This is a sweet little example, from above the car across to the right side of the photo. First and foremost, what this tells you is that water doesn't percolate into this unit well; it almost entirely runs off. This was established in the previous post, but here we're seeing another consequence of that fact. And since water doesn't get into that unit, it doesn't hold water in such a way that plants can easily get established. The exceptions to that rule are in spots where water is weeping out of the overlying contact, such as directly above the car.

The deeply dissected surface also tells you that the material in the lower unit erodes fairly easily. Soil development includes a number of processes, including weathering, accumulation of organic material,  biological succession and reworking on the surface, and the establishment of a sub-surface biota. But with bedrock like this, which is inhospitable to colonization, that's a long process. Add in the fact that every time there's a heavy rain, any accumulated weathering products and organic material are washed off, the process is reset to zero, and has to start all over. Until this face is worn down much closer to flat, or is covered by debris from deposition or mass movement, it will remain more or less bare.

Photo unmodified. October 9, 2012. FlashEarth Location.

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