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Gold Veins Near Great Falls, Maryland

Description: From abstract: Small deposits of native gold are present along an anastomosing system of quartz veins and shear zones just east of Great Falls, Montgomery County, Md. The deposits were discovered in 1861 and were worked sporadically until 1951, yielding more than 5,000 ounces of gold. The vein system and the principal veins within it strike a few degrees west of north, at an appreciable angle to foliation and fold axial planes in enclosing rocks of the Wissahickon Formation of late Precambrian … more
Date: 1969
Creator: Reed, John Calvin, Jr. & Reed, John Calvin
Item Type: Refine your search to only Report
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Chromite and Other Mineral Deposits in Serpentine Rocks of the Piedmont Upland, Maryland, Pennsylvania and Delaware

Description: From abstract: The Piedmont Upland in Maryland, Pennsylvania, and Delaware is about 160 miles long and at the most 50 miles wide. Rocks that underlie the province are the Baltimore gneiss of Precambrian age and quartzite, gneiss, schist, marble, phyllite, and greenstone, which make up the Glenarm series of early Paleozoic(?) age. These are intruded by granitic, gabbroic, and ultramafic igneous rocks. Most of the ultramafic rocks, originally peridotite, pyroxenite, and dunite, have been partly o… more
Date: 1960
Creator: Pearre, Nancy C. & Heyl, Allen V., Jr.
Item Type: Refine your search to only Report
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Primary Productivity by Phytoplankton in the Tidal, Fresh Potomac River, Maryland, May 1980 to August 1981

Description: Purpose and scope: The purpose of this study was to determine primary productivity and respiration of the fresh, tidal Potomac River. The data will be used by the authors and other researchers involved in modelling chemical and biological properties to calculate phytoplankton growth rates. Methods are documented in detail so that the report could serve as a reference. The report covers the period from May 1980 through August 1981. Five stations were selected for study that are representative of… more
Date: 1983
Creator: Cohen, Ronald R. H. & Pollock, Sheryl O.
Item Type: Refine your search to only Report
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