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An Ancient LakeWalking up Golden Canyon involves traveling through an ancient, changing landscape. It's time to again look closely at the rocks exposed in the canyon walls. You‘ll notice that the conglomerate layers composed of large boulders have given way to a different kind of rock. In contrast, these light-colored deposits are comprised of very small particles of silt and mud. Such fine-grained sediment is typical of debris that is deposited at the bottom of a calm lake. These mudstones are thought to be of similar age to the lower conglomerate. So the boundary between these different rock layers represents a change in the ancient landscape rather than a change in time or climate-you have walked across the alluvial fan and into a lake!
Ripples in TimeLook closely at the surface of the tilted rock layers in this area. Rather than being perfectly flat, some of the surfaces have an undulating pattern. If you are familiar with a lake or sea shore environment, perhaps you have observed similar ripples shaped in the sand. The ripple marks that you see here are further evidence of the ancient lake that once occupied this area; they were created by the movement of water over the loose sediment deposited at the bottom of the lake. The preservation of their delicate pattern required rapid burial beneath another layer of sediment. In other places in Death Valley, fascinating fossil footprints of large mammals have been found in lake deposits of similar age. |
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