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Merriam Cone, Crater Lake, Oregon

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[Merriam Cone Image]

Oblique view looking north toward Merriam Cone. The distance across the bottom of the image is about 1.8 kilometers (1.1 miles).

Merriam Cone, a symmetrical mound composed of andesite, was named for a former director of the Carnegie Institution of Washington. Its surface features and lack of a crater (compare to the Wizard Island cinder cone) indicate that it formed under water. The andesite composition of Merriam Cone is similar to that of deeply submerged parts of the Wizard Island volcano and to the southeast part of the central platform.

On the caldera wall north of the cone are steep outcrops (A) that extend far below the surface of the lake. Benches on the outcrops probably correspond to significant breaks in the growth of Mount Mazama. Above the lake, such breaks divide the mountain`s eruptive history into "packages" of lavas derived from specific source vents. Most of the rocks at this part of the shoreline are more than 120,000 years old, suggesting that the deepest outcrops below the surface stem from the mountain`s early history (see Chaski Bay and Phantom Ship ).

On the lake floor between Cleetwood Cove and Merriam Cone is a depression (B) that marks the approximate location of small pools of relatively warm water. These pools discovered in 1988 and 1989 by the researchers aboard the one-person submersible craft Deep Rover, are denser than overlying lake water because of higher concentration of dissolved salts. This location also marks the area of the highest measured heat flow in Crater Lake (Williams and Von Herzen, 1983).

Source: Gardner, James V., Peter Dartnell, Laurent Hellequin, Charles R. Bacon, Larry A. Mayer, and J. Christopher Stone. 2001. Bathymetry and selected perspective views of Crater Lake, Oregon. USGS Water Resources Investigations Report 01-4046.

March, 2001