Schematic Map of Glacial Lakes Missoula and Columbia

Schematic map showing glacial Lakes Missoula and Columbia
Schematic map showing glacial Lakes Missoula and Columbia Schematic map showing glacial Lakes Missoula and Columbia (blue). About 15,000 years ago, Lake Missoula burst through its glacial dam, sending massive amounts of water and sediment through the Columbia River drainage. Solid arrowed lines (left) show probable submarine pathways for turbidity currents that carried the sediment from the mouth of the Columbia River to Escanaba Trough (red rectangle at southern end of Gorda Ridge). Red circle with cross marks location of the Heceta submarine slide, which occurred about 110,000 years ago. This huge landslide blocked Astoria Channel, whose southern part (dashed red line) became abandoned. Thus, Astoria Channel could not serve as a pathway for the glacial turbidites 15,000 years ago. Offshore bathymetry modified from Grim et al. (1992), and subaerial features from Baker and Bunker (1985). Blue line at upper right indicates edge of the Cordilleran ice sheet.

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