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Crater Lake, Chaski Bay. Talus slope sits on flat top of massive sl...

2008 (approx.)

Detailed Description

View southwest of Garfield Peak and Eagle Crags above Chaski Bay. Cliffs at caldera rim are andesite of Applegate Peak (unit aa; ca. 210-270 ka), overlain by two thin flows of andesite of Garfield Peak at top center (unit ag; 224 ±9 ka). Talus rests on flat top of massive slide block that consists of altered lavas of units aa, ak(?), and db(?). Informally known as Chaski slide, the block was displaced downward from high on the caldera wall; an extensive debris-avalanche deposit lies on the caldera floor below Chaski Bay (Bacon and others, 2002). Several normal faults parallel to the caldera wall cut altered lavas below Garfield Peak, to the right of Chaski slide above Eagle Point. Yellowish-tan color results from oxidation of pyrite that is most evident in relatively permeable, flow-top breccias.


Public Domain.

Bacon C.R., 2008