| Woodstock Quartz Monzonite | |
|---|---|
| Stratigraphic range: Silurian or Ordovician | |
 Photographed on a boulder in Granite, Maryland | |
| Type | igneous |
| Area | ~400 Ha |
| Lithology | |
| Primary | monzonite |
| Location | |
| Region | Piedmont of Maryland |
| Country | United States |
| Extent | Western Baltimore County |
| Type section | |
| Named for | Woodstock, Maryland |
| Named by | Williams and Darton, 1892[1] |
The Woodstock Quartz Monzonite is a Silurian or Ordovician quartz monzonite pluton in Baltimore County, Maryland. It is described as a massive biotite-quartz monzonite[2] which intrudes through the Baltimore Gneiss at a single locality surrounding the town of Granite, Maryland.
The extent of this intrusion was originally mapped in 1892[1] as the "Woodstock granite". It was given its current name in 1964 by C. A. Hopson.[3] Hopson grouped the Woodstock Quartz Monzonite with the Ellicott City Granodiorite and the Guilford Quartz Monzonite as "Late-kinematic intrusive masses."
Woodstock granite has been used in the Capitol Building, the Library of Congress, and in buildings in Baltimore.[4]
- ^ a b Williams, G.H., and Darton, N.H., 1892, Geologic map of Baltimore and vicinity: U.S. Geological Survey, Map to accompany "Guide to Baltimore".
- ^ USGS Mineral Resources On-Line Spatial Data
- ^ Hopson, C. A., 1964, The crystalline rocks of Howard and Montgomery Counties: Maryland Geological Survey County Report, 337 p., (Reprinted from Cloos, Ernst, and others, "Geology of Howard and Montgomery Counties," p. 27-215)
- ^ Park, John R (2002). Maryland mining heritage guide: including Delaware and the District of Columbia. Miami, FL: Stonerose Pub. Co. p. 35. ISBN 0970669720.