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|A Geologic Walking Tour of Building Stones of Downtown Baltimore, Maryland||contact: Dale Shelton (email@example.com)|
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STOP 10: CITY OF BALTIMORE POLICE HEADQUARTERS - 601 East Fayette Street
Continue walking east along Fayette Street to the Police Headquarters. This building and the pedestals for the flag poles are faced with Rainbow Gneiss (also known as Morton Gneiss) from Morton, Minnesota (Figures 10a and 10b).
This gneiss is about 3.6 billion years old, one of the oldest rocks in North America. The name is well suited for the contorted bands of black biotite mica, pink feldspar, and gray quartz. The polished finish highlights the grain and texture of this ancient and attractive Precambrian building stone.
10a: Polished Rainbow Gneiss on the west
wall of the City of Baltimore Police Headquarters (Stop 10); photo
width corresponds to a distance of about 12 feet.
This pamphlet was prepared by
Sherry McCann-Murray, with contributions and photography by the Environmental
Geology and Mineral Resources Program of the Maryland Geological Survey.
Adapted for the Internet from Educational Series No. 10. For more information see Building Stones of Maryland .
Compiled by the Maryland Geological Survey, 2300 St. Paul Street, Baltimore, MD 21218
This electronic version of "A Brief Description of the Geology of Maryland " was prepared by Bob Conkwright, Division of Coastal and Estuarine Geology, Maryland Geological Survey. Please send comments on this page to Dale Shelton (firstname.lastname@example.org)
State of Maryland
Department of Natural Resources, Resource Assessment Service