Here at the head of Afton Canyon we are looking at the yellow-green clay deposits of Lake Manix (arrow), that have since their origin been mostly eroded away after the dam was breached and eroded. Deposits below the ledge at the level of Frank Hanna's hat and George Dunne's nose are river and alluvial fan deposits that crept out across the lake basin when there was no water in the lake. As the lake filled during one of the glacial stages, the surrounding rivers were forced to deposit their sediment in deltas around the edges of the lake and the center of the lake received only clay deposits. Above the lake deposits, not seen in the picture, is another set of river deposits marking the draining or evaporation of the lake and the advancement of the surrounding rivers into the center of the playa. After four days in the field, we had all learned a great deal and owe a big thank you to George Dunne, Bob Howard, and Frank Hanna, the field trip leaders.
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