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DGS Annual Report

DGS Annual Report of Programs and Activities.

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Site content related to keyword: "Shellpot Creek"

Stream Station: Shellpot Creek at Wilmington

USGS 01477800 SHELLPOT CREEK AT WILMINGTON, DE

Station Type: 
Stream
Period of Record: 
1945 to Present
Frequency: 
Monthly
Map County: 
New Castle County
Map Location: 
39.760972,-75.5186944

Outcrop Bd44-b: Bringhurst Gabbro boulders in Shellpot Creek

Rock Outcrop Bd44-b: Bringhurst Gabbro boulders in Shellpot Creek

Found in the creek bed and flood plain, the large boulders in Shellpot Creek are excellent examples of Bringhurst Gabbro. The gabbro is very coarse-grained with crystals up to 2" long; however, variations in the grain size exist over a scale of a few inches. While observing this rock closely, one can occasionally find grains of orthopyroxene (possibly bronzite) up to 4" long. Some of the boulders have grains of olivine surrounded by double coronas of orthopyroxene, spinel, and hornblende.

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.