A BRIEF GEOLOGIC HISTORY OF ROCKINGHAM COUNTY
By W. Cullen Sherwood
Dept. of Geology and Environmental Studies
James Madison University
INTRODUCTION
During this period of bicentennial celebration for the city of Harrisonburg it is appropriate to take a brief look at another aspect of the past, the geologic history of the Harrisonburg-Rockingham County area. The term "history" is usually thought of in terms of human lives and activities and indeed the Harrisonburg-Rockingham area is rich in these terms. However, geologists working in the Valley area have found evidence of a rich and varied history which can be traced back thousands of millennia prior to the arrival of man on this continent. This aspect of history, known as geologic history, is well recorded in the rocks which underlie Harrisonburg and Rockingham County. These rocks reveal a rich history with events ranging from shallow tropical seas to Alpine-sized mountain ranges existing here in the past. This paper will attempt to describe these events based on the evidence geologists have found in their studies of the rocks.
Studies involving the geology of the Valley have been undertaken periodically over a period of nearly 150 years. One of the first of these was published by University of Virginia geologist Henry Barton Rogers in 1853. Rogers, who subsequently left the University to found the Massachusetts Institute of Technology, was a keen observer and first described many of the rocks and other geologic features which are available for our study today. Following Rogers' work many studies of the geology of Rockingham have been undertaken. Some of the best known are those by Butts (1940), Brent (1960), and Hack (1965). Recent interest in potential oil and gas deposits in the county has brought in geologists from as far away as Texas. These geologists using space age technology should provide even greater insights and clues to the local geologic past in the months and years ahead.