Brighton Dam Road Quarry (Howard-Montgomery Quarry), Howard Co., Maryland, USA
|Latitude & Longitude (WGS84):||39° 11' 44'' North , 76° 59' 9'' West|
|Latitude & Longitude (decimal):||39.19556,-76.98583|
|Köppen climate type:||Cfa : Humid subtropical climate|
This quarry was in a somewhat schistose to gneissic phase of the Cockeysville Marble along the southern flank of the Clarksville gneiss dome. It was operated by the Howard-Montgomery Crushed Stone Company, a division of Contee Sand and Gravel. The Howard/Montgomery Quarry is now filled with water and is located in the middle of an upscale residential neighborhood. The grounds of the quarry are posted "No Trespassing."
14 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
541 - 2500 Ma
Age: Proterozoic (541 - 2500 Ma)
Stratigraphic Name: Cockeysville Marble
Comments: secondary unit description from USGS Geologic Names lexicon (ref MD004): Author has erected a six-fold stratigraphy for the Cockeysville consisting of five unnamed members and one lens to accommodate the variety of rock types. These are the layered marble member (0 to 200 m), the massive metadolostone member (0 to 400 m), the layered metadolostone member (0 to 1.4 km), the massive metalimestone member (0 to 450 m), which includes the calc-gneiss lens (0 to 225 m), and the phlogopitic metalimestone member (0 to 300 m). Each member is described in detail. Thickness of the Cockeysville overall varies from 0 to 1.4 km, the range of the layered metadolostone. The relative ages of these units are uncertain. Unit as a whole is mapped as Cambrian to Ordovician(?).
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. 
MESA Health and Safety Inspection Report January 31 & February 1, 1972.
Bernstein, Lawrence (1980) Minerals of the Washington D. C. area: Maryland Geological Survey Educational Series 5, 148 p.