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DGS Annual Report

DGS Annual Report of Programs and Activities.

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Site content related to keyword: "Ardentown"

Biotite Tonalite

Sbt

Fine- to medium-grained, equigranular biotite tonalite usually occurring as rounded boulders. Tonalites are leucocratic (15 to 25% modal mafic minerals), light gray to buff on fresh surfaces, and locally contain mafic enclaves with reddish rims, the result of iron hydroxide staining. Possibly intrusive into the Perkins Run Gabbronorite Suite.

Outcrop Be22-k: Charnockite Boulders at Ardentown

Rock Outcrop Be22-k: Charnockite Boulders at  Ardentown

In the valley of the South Branch of Naaman Creek, through Ardentown, is a group of charnockite boulders and fine-grained mafic rock (probably amphibolitized gabbroid). The mafic rock is mostly non-megacrystic with some coarse-grained and equigranular charnockite. On the ground around the boulders are small pieces that contain a clear example of a contact between coarse-grained and fine-grained rock types.

RI59 Bedrock Geology of the Piedmont of Delaware and Adjacent Pennsylvania

RI59 Bedrock Geology of the Piedmont of Delaware and Adjacent Pennsylvania

This report accompanies a new map that revises the original bedrock geologic maps of the Delaware Piedmont compiled by Woodruff and Thompson and published by the Delaware Geological Survey (DGS) in 1972 and 1975. Combined detailed mapping, petrography, geochemistry, and U-Pb geochronology have allowed us to redefine two rock units and formally recognize eleven new units. A section of the Pennsylvania Piedmont is included on the new map to show the entire extent of the Mill Creek Nappe and the Arden Plutonic Supersuite.