Foreword

Introduction

Acknowledgments

Overview

Water Use

Topography of the County

Geology of the County

Groundwater Availability

Exploration for Groundwater

Karst

Water Quality

Maps and Data

Additional Reading

References Cited

Definitions of Geologic Terms

Rock Descriptions

In Harrison County, water is obtained from consolidated sedimentary rocks of Ordovician age and unconsolidated sediments of Quaternary age. The oldest rocks found on the surface in Harrison County, the Lexington Limestone, were deposited in shallow seas 490 million years ago during the Ordovician Period. In the Late Ordovician the seas became relatively shallow, as indicated by the amounts of mud (shale) in the sediments. When the waters were clear and warm, a profusion of animal life developed, particularly brachiopods and bryozoa. Over the last million years, unconsolidated Quaternary sediments have been deposited along the larger streams and rivers.

Geologic Formations in the County
Unconsolidated deposits
Alluvium (Qa)

Limestones
Lexington Limestone (Tanglewood Limestone, Grier, Logana Members) (Ol)

Interbedded limestones and shales
Clays Ferry Formation and its Point Pleasant Tongue (Okc)

For more information, see the definitions of geologic terms and rock descriptions, a geologic map of Harrison County, a summary of the geology of Kentucky, and a discussion of fossils and prehistoric life in Kentucky.

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