1. Generalized bedrock geologic map of the Helena area, west-central Montana Author/Creator: Reynolds, Mitchell W. Publication/Creation: [Reston, Va.?] : U.S. Dept. of the Interior, U.S. Geological Survey, 2002 Resource Type: Map Edition: Version 1.0, last modified 07-Aug-2002. Access & Availability: Loading
2. Geologic map of the Canyon Ferry Dam 30ʹ x 60ʹ quadrangle, west-central Montana Author/Creator: Reynolds, Mitchell W. Publication/Creation: Denver, Colo. : U.S. Geological Survey, 2005 Resource Type: Map Access & Availability: Loading