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Discovery park seattle photos11/10/2023 ![]() ![]() The Lawton Clay accumulated at the bottom of these large lakes.Ībove the Lawton Clay in the photograph are steeper cliffs of Esperance Sand. The dammed rivers formed a series of large lakes. Clay accumulates at the bottom of lakes or relatively stagnant bodies of water.Īs it entered the northern part of the Puget Sound basin, the advancing Vashon glacier probably dammed the drainage of the rivers whose sediments are seen in the Olympia Interbeds. The Lawton Clay, like any clay that is deposited in broad, flat layers, indicates that a large body of low-energy water was present. Use your browser's back button to return to this page. The Lawton Clay, like most clay, is a weak, soft material that turns into slippery mud when wet. That zone where the grass and trees grow is where the Lawton Clay is located. This picture shows the Olympia Interglacial beds up to the break in slope, the point at which the slope becomes less steep and where many tufts of grass and a lone, dying tree grow. Possession Formation, Lawton Clay, Esperance Sand Higher in the bluffs, above these Olympia Interglacial beds, is a sequence of sediments that records the approach and arrival of the Vashon glacier. The Olympia Interglacial beds at the top of this picture are partly covered by blue-gray clay that has flowed down from the next layer of sediment above. The beds in the picture are evidence of those rivers, with ripples in the beds of sand indicating water flowing in broad, shallow stream channels silt-plus-clay-rich layers indicating ponds and backwaters and woody debris indicating trees, bushes and small plants growing in the area. During the interglacial, meandering streams and rivers flowed north toward the sea, across what is now the Puget Sound region. The layers of sediment in this picture record the Olympia Interglacial interval, the time before the approach of the Vashon glacier. At high tide, the waves of Puget Sound lap up against this outcrop. The base of the bluff in this photo is composed of sedimentary beds. At Discovery Park, on Puget Sound in Seattle, a high bluff (sea cliff) shows a record of events that mark the coming of the Vashon glacier that filled the Puget Sound region.
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