Inskip Hill

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On this butte there is a colony of MacNab cypress, Cupressus macnabiana, growing in association with gray pine, Pinus sabiniana, and chaparral. This cypress, which is found in isolated stands in the northern Sierra and Coast Ranges, is separated some 16 kilometers (10 miles) from the nearest population to the north and 48 kilometers (30 miles) from the nearest to the east.

The hill is of volcanic origin and has numerous lava outcrops. It is part of a Plio-Pleistocene volcanic activity that began some miles to the east with the now vanished Mt. Maidu. From this cone issued first flows of basaltic andesite, followed by pyroxene andesite and dacite. Some 1.5 million years ago two enormous eruptions spewed forth rhyolite which covered some 180 square kilometers (70 square miles) to an average thickness of 152 meters (500 feet), followed by dacite avalanches which covered perhaps as third as great an area. The summit of Mt. Maidu collapsed, forming a caldera. Later came a series of basalt eruptions that built cinder cones with associated lava flows. Inskip Hill is one of these and dates to the mid or late Pleistocene.

There are ice caves on the hill.

Integrity: There is a lookout station atop the hill and a road leading to it.

Use: Private

Ref: Wilson, T. A. 1961. The Geology near Mineral, Cal. Unpub. M.S. Thesis, Univ. of Cal., Berkeley
Griffin, James and C. 0. Stone, 1967, MacNab Cypress in Northern California: A Geographic Review. Madrono 19, pp. 19-27.

August 1975

Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman

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