Near Two Harbors in Lake County, Minnesota — The American Midwest (Upper Plains)
Geology of Minnesota
Split Rock Region
Lava flows, which had accumulated in this region to a thickness of about 30,000 feet, were lifted and arched by a huge mass of molten material rising through the earth's crust farther north. This mass, this Duluth Gabbro, is now extensively exposed in the Duluth area.
The lighthouse cliff standing 100 feet high is a fine-grained phase of Gabbro named Beaver Bay diabase. The massive resistant character of which makes the shore of this region particularly bold and rocky.
At the base of the lighthouse on top of the cliff is another kind of rock, light green in color and coarse in texture, called Anorthosite. It is this rock, Anorthosite, which shows an excellent exposure in the highway cut at Silver Bay and stands up as prominent rounded hills from Split Rock to Carlton Peak near Tofte.
Erected 1955 by Geological Society of Minnesota and the Department of Highways, State of Minnesota.
Topics and series. This historical marker is listed in this topic list: Environment. Minnesota: Geological Society of Minnesota series list.
Location. 47° 11.957′ N, 91° 22.779′ W. Marker is near Two Harbors, Minnesota, in Lake County. Marker can be reached from State Highway 61, 3 miles north of Blueberry Hill Road. Located in a Wayside just south of Split Rock Lighthouse. Touch for map. Marker is in this post office area: Two Harbors MN 55616, United States of America. Touch for directions.
Other nearby markers. At least 3 other markers are within walking distance of this marker. Anchor of the Madeira (approx. 0.6 miles away); Steam Hoist Engine (approx. 0.6 miles away); The Gales of November (approx. 0.6 miles away).
Credits. This page was last revised on June 16, 2016. It was originally submitted on August 15, 2014, by Mike Wintermantel of Pittsburgh, Pennsylvania. This page has been viewed 418 times since then and 16 times this year. Photos: 1, 2. submitted on August 15, 2014, by Mike Wintermantel of Pittsburgh, Pennsylvania.