igneous
OFR54 Bedrock Geologic Map of the Delaware Piedmont
The Piedmont rock units in Delaware, and bedrock geologic map of Schenck et al. (2000) are revised in this report based on new rock geochemistry, geochronometric data, petrography, and recent detailed mapping. Major revisions include:
William “Sandy” Schenck participated in the Manhattan Prong Workshop Sep 6-7, 2014.
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The Rocks of the Manhattan Prong show similar tectonic, metamorphic, sedimentary, geomorphic, and igneous features to our own rocks here in northern Delaware and southeastern Pennsylvania.
A.I.duPont Students see geology of the Delaware Piedmont
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William "Sandy" Schenck lead a field trip through the Delaware Piedmont for the A.I. duPont High School Earth Science Class. The trip made use of the Wilmington-Western Railroad and everyone rode the railroad's "Doodle Bug." Activities included up close examinations of rock and mineral features and even "Panning for Garnets" at Brandywine Springs Park.
Biotite Tonalite
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.
The Bringhurst Gabbro: A GeoAdventure in the Delaware Piedmont
A field trip to Bringhurst Woods Park is appropriate for students in grades 5 and up (10 years and older), and provides an opportunity to observe intrusive plutonic igneous rocks that have intruded into country rock, which in this case is the blue rock or what geologists call the Brandywine Blue Gneiss. In addition, the minerals in the pluton are large, easily identified, and interesting. Mineral collecting is not allowed within the park, however permission may be obtained to collect along Shellpot Creek southeast of the park. Please do not use rock hammers on the rocks in the park.
What are GeoAdventures?
GeoAdventures are designed to allow the reader to learn about a particular geologic point of interest in Delaware’s Piedmont province and then take a short field trip to that area. Want to know more about the Wilmington blue rock or Brandywine blue granite? Take the Wilmington Blue Rock GeoAdventure and go see just what the blue rock looks like.
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