Antietam Formation

The Antietam Formation or Antietam Sandstone is a geologic formation in Pennsylvania, Maryland and West Virginia.^[2][3][4] It is largely quartz sandstone with some quartzite and quartz schist. It preserves Skolithos trace fossils dating back to the Cambrian Period.^[5]

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  Tight folds in the schist of Antietam Formation
• 
  Thin section of schist. Porphyroblastic biotite, a, in a dolomitic matrix. The tourmaline, t, is epigenetic.

Antietam Formation
Stratigraphic range: Cambrian
Anticline in schist of Antietam Formation
Type	Formation
Unit of	Chilhowee Group
Underlies	Tomstown Dolomite
Overlies	Harpers Formation
Thickness	550 ft
Lithology
Primary	Sandstone, quartzite
Other	Schist
Location
Region	Appalachia, Eastern United States, and Southeastern United States
Country	United States
Extent	Maryland, Pennsylvania, Virginia,[1] and West Virginia
Type section
Named for	Antietam Creek