|Geologic Map Legends|
|Western Piedmont Metasedimentary Rocks|
The information contained on this page was adapted from Maryland Geological Survey's Geologic
Map of Maryland (1968). This information reflects geologic interpretations from over
20 years ago and do not necessarily represent an accurate interpretation of currently accepted
geologic theory. We present this information for historic purposes only. Do not use this information
for anything other than illustrative purposes. When a corrected and updated geologic map of
Maryland is available you will see a notification on our web site.
Dark gray to green sericite-chlorite phyllite, metasiltstone, and quartzite; thin lenses of impure marble and calcareous phyllite occur locally.
|Sugarloaf Mountain Quartzite
Massive white quartzite interbedded with softer sericitic quartzite, slate, and phyllite.
Purple, bluish-black and red, dense, fine-grained metarhyolite with feldspar phenochrysts; interbedded with blue and purple amygdaloidal metaandesite; both rhyolite and andesite interbedded with blue, purple, and green phyllitic slates.
|Sams Creek Metabasalt
Grayish-green, massive to schistose, amygdaloidal metabasalt.
White, fine-grained marble; subordinate white, green, and pink variegated marble; and blue marble.
|Silver Run Limestone
Blue, thin-bedded, finely crystalline schistose limestone and calcareous slate.
Blue, green, or purple phyllite and phyllitic slate, with interbedded metasiltstone and metagraywacke; flattened pumiceous blebs occur locally.
Bluish-gray to silvery-green, fine-grained, muscovite-chlorite-albite-quartz schist; intensely cleaved and closely folded; contains interbedded quartzites.
Please note the changes in the former "Wissahickon formation" nomenclature that are presented on the Eastern Piedmont Metasedimentary Rocks page.