Educational Series 10. Geology of the Root River State Trail Area, Southeastern Minnesota

Abstract

The Root River State Trail is a paved walking, bicycling, and cross- country skiing trail in southeastern Minnesota that currently extends from the town of Fountain through Lanesboro to Rushford, and farther east towards Houston. It is maintained by the Minnesota Department of Natural Resources, which operates a trail information center in Lanesboro. The Rushford Historical Society operates a trail rest area in Rushford. The trail is part of a planned network of trails throughout southeastern Minnesota, that will ultimately extend into Iowa and Wisconsin. This guide was developed for the Fountain to Rushford segment of the Root River State Trail, but the information will help you learn more about geologic features you see anywhere in southeastern Minnesota. The Root River State Trailtraverses the unique landscape of Minnesota's 'Historic Bluff Country,' and provides us with a birds-eye- view into the processes that have been forming the rocks and the land surfaces in this part of Minnesota during the past 500 million years. Flat- lying layers of limestone and dolostone form high bluffs above narrow river valleys, such as the Root River valley. The limestone uplands are intensively farmed, but many of the fields contain pits or depressions, called sinkholes, that surface water drains into. The sinkholes are usually overgrown with burr oak, stinging nettle, woodbine, and wild cherry. The Root River has eroded a steep-sided valley into the layers of limestone and dolostone. At the base of the cliffs, water that drained into the sinkholes on the uplands emerges as springs, having traveled through passageways in the limestone and dolostone. This booklet summarizes the history of the rocks that you see as you explore the Root River State Trail, and presents a field guide to features of geologic interest.