An exposure of the Pottsville Formation. The Pottsville is a very coarse-grained sandstone that makes up much of the Allegheny Front.

Buttermilk Falls in Beaver County. Homewood Sandstone (link is external), a common building material in 19th century western Pennsylvania, was quarried on the site.

Wycoff Run Waterfall in Cameron County, PA.

Small stream cutting through Shingletown Gap near State College.

Large diabase boulders at Devil's Den, Gettysburg National Park.

Outcrop of Bald Eagle sandstone at Shingletown Gap. Bald Eagle and Tuscarora sandstones make up many of the ridges of the central part of PA. 

PAESTA member Dave Curry came across an exciting prehistoric find on an exposed limestone outcrop while he and group of PAESTA members explored the Acid Mine Drainage (AMD) Remediation Project along the North Fork of the Montour Run.  Members of PAESTA were exploring this site as part of the K12 Teacher Weekend field trip during the 2017 NE/NC Joint GSA Conference in Pittsburgh.  This edge-on cross section of a Paleozoec horn coral was deposited in a warm, shallow sea sometime in the late Ordovician or Permian, some 251 to 488 million years ago.  Horn corals, which are distantly related to jellyfish, are solitary corals that are now extinct, as they died out during the Great Permian Extinction (The Great Dying).  This greatest of mass extinctions wiped out 96% of all marine species and 70% of all land species.  Thanks to the Montour Run Watershed Association (http://www.MRWA.info (link is external)) and Karen Rose Cercone of IUP for organizing the trip!

Note: This fossil-rich limestone may have been unearthed (not in its original site of deposition) and moved during coal extraction in this strip and deep mining coal area.

Full Taxonomic CLassification:

Domain: Eukarya

Kindom: Animal (Animalia)

Phylum: Cnidaria (Coelenterata)

Class: Anthozoa

Subclass: Zoantharia (Hexacorallia)

Order: Rugosa (rugose means wrinkled, which describes the outside horn shape)

Family: Zaphrentidae

Genus: Heliophyllum