Dark gray porphyry spotted with rectangular white feldspar phenocrysts from head of Marsh Creek hollow. Adams County, Pennsylvania. 1927.
Dates
Date Taken
1927
Summary
Dark gray porphyry spotted with rectangular white feldspar phenocrysts from head of Marsh Creek hollow. Polished specimen. Adams County, Pennsylvania. 1927. Plate 32 in U.S. Geological Survey. Folio 225. 1929.
Summary
Dark gray porphyry spotted with rectangular white feldspar phenocrysts from head of Marsh Creek hollow. Polished specimen. Adams County, Pennsylvania. 1927. Plate 32 in U.S. Geological Survey. Folio 225. 1929.
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