Geology and Minerals

Hogg Rock

Hogg Rock is a tuya volcano and lava dome in the Cascade Range of northern Oregon, United States, located close to Santiam Pass. Produced by magma with an intermediate andesite composition, it has steep slopes and thick glassy margins. Hogg Rock exhibits normal magnetic polarity and is probably about 80,000 years old. Hogg Rock lies south of Three Fingered Jack and north of Hayrick Butte, a somewhat larger tuya of similar age and composition. A tuya is a type of subglacial volcano, formed when lava erupts underneath an overlying glacier or ice sheet and then melts through to the surface and pools, producing the flat plateau on top with near-vertical walls along the ice-contact margin as the lava cools and hardens. It is a historic landmark, with the remnants of Colonel T. Egenton Hogg's Oregon Pacific Railroad, the Santiam Lodge, and a quarry. The mountain offers snowshoe and snowmobile trails, and its summit provides views of the surrounding area including volcanoes like the Black Butte stratovolcano, Mount Washington, Sand Mountain, and Potato Hill.

Also on this shelf

See also

• ▸1888 eruption of Mount Bandai
• ▸Arturo O'Farrill
• ▸Ediacaran

Uncatalogued shelf

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