Bulletin of the National Speleological Society - ISSN 0146-9517
Volume 35 Number 2: 49-58 - April 1973

A publication of the National Speleological Society

Scapegoat Alpine Karst, Montana
Newell Campbell

Abstract

The Scapegoat Mountain alpine karst area is a high plateau lying in the center of the Scapegoat Wilderness, 75 miles west of Great Falls, Montana. The plateau is underlain by more than 1,700 feet of Cambrian rocks, part of the upper plate of a large thrust sheet. Nearly 1,000 feet of Middle Cambrian carbonates cap the 8,000 foot plateau and solution features are widely scattered over the plateau surface. Solution features range from pits several hundred feet deep to small karren less than an inch wide. All of the karst is developed along three joint sets, N20E, N35W and N65W.

The location of the larger sinkholes is controlled by the position of large north-south trending snowbanks that drift in during the winter months. More melt-water is available for solution beneath these snowbanks, allowing larger pits to develop there than elsewhere.

All runoff from the Scapegoat Plateau is channeled underground through sinkholes and resurges from caves in the canyon walls 1,000 feet below. Mapping of several of these caves in the canyon walls 1,000 feet below. Mapping of several of these caves revealed that the joint pattern is consistent throughout the carbonate section. The age of the karst probably is post-Pleistocene.

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