Tremont Syncline

 Folded Rocks along Interstate 81                                                      Photo by Stuart Reese

The Tremont Syncline is exposed along a road cut of Interstate 81, just north of Exit 107 in Schuylkill County. This downfold was formed approximately 290–250 million years ago during the Alleghanian mountain building episode. The rocks exposed here are from the Llewellyn Formation, an important coal-bearing rock unit in eastern Pennsylvania.