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

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AMC Raises LWCF Awareness at Valley Forge National Historical Site

Appalachian Mountain Club Delaware Valley Chapter outdoor leader and conservation chair joined 11 hikers at Valley Forge National Historical Park to hike 6 miles and talk about the importance of the Land and Water Conservation Fund on Wednesday, October 30th. Read More

PA Highlands Coalition Hosts Local Funding Webinar

On Thursday October 31st, 2019 the PA Highlands Coalition hosted “Match Funding: Open Space Referendums and other local tools to support Land Conservation” during a one-hour webinar. Read More

AMC Highlights LWCF at Washington Crossing State Park

On Wednesday, October 30th, AMC Delaware Valley Chapter outdoor leader and Mid Atlantic conservation policy staff joined 36 hikers to walk 9 miles and talk about the importance of the Land and Water Conservation Fund. Read More

PA Highlands Coalition to Host Local Funding Webinar

On Thursday, October 31st, 2019 at 2pm, the PA Highlands Coalition will host the webinar “Match Funding: Open Space Referendums and other local tools to Support Land Conservation.” Read More