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Mountains, glaciers, and mines—The geological story of the Blue River valley, Colorado, and its surrounding mountains

Circular 1400
By: , , and 
https://doi.org/10.3133/cir1400

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Abstract

This report describes, in a nontechnical style, the geologic history and mining activity in the Blue River region of Colorado, which includes all of Summit County. The geologic story begins with the formation of ancient basement rocks, as old as about 1700 million years, and continues with the deposition of sedimentary rocks on a vast erosional surface beginning in the Cambrian Period (about 530 million years ago). This deposition was interrupted by uplift of the Ancestral Rocky Mountains during the late Paleozoic Era (about 300 million years ago). The present Rocky Mountains began to rise at the close of the Mesozoic Era (about 65 million years ago). A few tens of millions years ago, rifting began to form the Blue River valley; a major fault along the east side of the Gore Range dropped the east side down, forming the present valley. The valley once was filled by sediments and volcanic rocks that are now largely eroded. During the last few hundred-thousand years, at least two periods of glaciation sculpted the mountains bordering the valley and glaciers extended down the Blue River valley as far south as present Dillon Reservoir. Discovery of deposits of gold, silver, copper, and zinc in the late 1800s, particularly in the Breckenridge region, brought an influx of early settlers. The world-class molybdenum deposit at Climax, mined since the First World War, reopened in 2012 after a period of closure.

The report includes a glossary to explain geologic terms used in the text, and numerous photos, maps, and diagrams illustrate the geologic principles discussed. References for further reading are also included. 

Suggested Citation

Kellogg, K.S., Bryant, Bruce, and Shroba, R.R., 2016, Mountains, glaciers, and mines—The geological story of the Blue River valley, Colorado, and its surrounding mountains: U.S. Geological Survey Circular 1400, 46 p., http://dx.doi.org/10.3133/cir1400.

ISSN: 2330-5703 (online)

ISSN: 1067-084X (print)

Study Area

Table of Contents

  • Overview of This Report
  • Introduction
  • The Rise of the Rocky Mountains
  • The Continent Pulled Apart—Development of the Northern Rio Grande Rift
  • The Ice Ages
  • Landslides and Spreading Mountains
  • Rich Ores of the Blue River Valley Region—Their Geology and Mining History
  • Acknowledgments
  • Suggested Reading
  • Glossary
Publication type Report
Publication Subtype USGS Numbered Series
Title Mountains, glaciers, and mines—The geological story of the Blue River valley, Colorado, and its surrounding mountains
Series title Circular
Series number 1400
ISBN 978-1-4113-3966-8 (pbk.)
DOI 10.3133/cir1400
Year Published 2016
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Geosciences and Environmental Change Science Center
Description vii, 44 p.
Country United States
State Colorado
County Summit County
Other Geospatial Blue River valley
Online Only (Y/N) N
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details