Pennsylvania Highlands Geology

The Pennsylvania Highlands are the foothills of the Appalachian Mountains. The irregular ridges and deep valleys of this unique landscape feature common themes that reflect the region’s geology, which has influenced local history and land use. Much of the Pennsylvania Highlands are comprised of the Reading Prong Geologic Formation. The Reading Prong is found primarily in Berks, Bucks, Montgomery, and Northampton Counties.

Two types of rock are common to the erosion resistant, largely forested ridges of the Pennsylvania Highlands: diabase (basalt), and granitic gneiss and quartzite (see map). The diabase areas create natural limitations for agriculture and land development, due to the size and abundance of boulders. As a result, these areas feature large contiguous woodlands such as Hopewell Big Woods and Unami Hills.

The high iron content in the gneiss and quartzite rock ridges provided the raw material for the region’s industrial legacy of iron and steel. This legacy is reflected in the names of towns, historic sites and parks found throughout all thirteen counties of the Pennsylvania Highlands region: places such as Durham Furnace, Coventry Forge, Hopewell Furnace, Johanna Furnace, Cornwall Furnace, and Pine Forge Furnace. The desire for a  recreation resource connecting these historic areas and unique natural resoures was the impetus for the development of the Pennsylvania Highlands Trail Network. The unique combination of forests, rocky hills, historic sites, industrial towns, and fertile limestone valleys makes for a compelling story told through interpretive signage and online tools, enhancing the experience of trail users.

Diabase boulders along the Unami Creek, Montgomery County

News

Click here to see all news

Highlight the Highlands: Hopewell Furnace National Historic Site Celebrates National Public Lands Day

10/3/19 — In the PA Highlands, on Saturday September 28th, Hopewell Furnace National Historic Site hosted a NPL Day event to preserve and protect the natural and cultural resources of the site. Read More

Highlight the Highlands: Valley Forge National Historical Park Celebrates National Public Lands Day

10/2/19 — In the heart of the PA Highlands, citizens celebrated National Public Lands Day at Valley Forge National Historical Park by engaging in voluntary trail work on Saturday, September 28th. Read More

Highlight the Highlands: Pine Grove Furnace State Park Celebrates National Public Lands Day

10/1/19 — In the western section of the PA Highlands, community members celebrated National Public Lands Day at Pine Grove Furnace State Park by planting 30 native trees on Saturday, September 28th. Read More

Unami Creek Greenway Project Public Meeting

The Appalachian Mountain Club has partnered with Heritage Conservancy to study land conservation and trail development along the Unami Creek in Milford Township, Bucks County. Read More