Introduction: In 1978 the U.S. Geological Survey began a 4-year study of aquifers in the northern Great Plains. The purpose of this map, which is a product of that study, is to show the altitude of the top of the Lakota Formation and equivalent rocks. Other maps show the total thickness (Feltis, 1982a), cumulative thickness of sandstone (Feltis, 1982b), and potentiometric surface of water (Levings, 1982) in the Lakota Formation and equivalent rocks. These maps are part of a series that describes the geology and potentiometric surface of selected rock units of Jurassic or younger age in the plains area of Montana.

From introduction: In 1978 the U.S. Geological Survey began a 4-year study of aquifers in the northern Great Plains. The purpose of this map, which is a product of that study, is to show the total thickness of the Lakota Formation and equivalent rocks.

Introduction: In 1978 the U.S. Geological Survey began a 4-year study of aquifers in the northern Great Plains. The purpose of this map, which is a product of that study, is to show the cumulative thickness of sandstone in the Lakota Formation and equivalent rocks. Other maps show the altitude of the top (Feltis, 1982a), total thickness (Feltis, 1982b), and potentiometric surface of water (Levings, 1982) of the Lakota Formation and equivalent rocks. These maps are part of a series that describes the geology and potentiomentric surface of a selected rock units of Jurassic or younger age in plains area of Montana.

A report about lithium inside of clay minerals. Lithium can be present in clays as impurities, inclusions, lattice cavities, or by isomorphous substitution.

From introduction: The purpose of this report is to: (1) Present flood data for the gaged sites used in the flood-frequency analysis. (2) Describe the method of analysis used to develop the flood-estimating technique. (3) Provide regression equations for estimating floods on natural-flow (unregulated) streams. (4) Provide a method for improving the flood estimate at gaged sites. (5) Provide illustrative examples of applying the flood-estimating technique.