Dipboye Cirque is quite different from our other camp sites. For the first time we can see the headwall or starting location of the glacier. In addition the small glacier has a well-developed modern moraine. This moraine is special because it changes color as you look from left to right.
 |
| The “baby” glacier with its modern moraine. |
On the left side the moraine is a dark brown color and the right side is a light tan color. The different colors reflect a difference in rock type. The left side of the modern moraine is composed of dolerite, a dark volcanic rock while the right side is almost entirely sandstone. If you look at the large rock outcrop behind the glacier you might be able to guess why the moraine looks like this. At the top left there is a small dark brown dolerite outcrop and to the top right the rock outcrop is all sandstone. These rocks fall onto the glacier in the same distribution, eventually becoming stuck in the ice. Once the ice has a hold of the rocks they will flow into the glacier and after a while these rocks will come out of the glacier and be deposited in its modern moraine.
 |
| Diagram showing how a rock (tan circle) would flow through a glacier and be deposited at its end. |
No comments:
Post a Comment