Pennsylvania Legacies #157: Rock Talk

Resources

From the formation of fossil fuel deposits to the tectonic ballet that gave us the Appalachian Mountains, geologic events occurring hundreds of millions of years ago made the Keystone State what it is today. These events also created the distinctive regional topographies by which DCNR’s Conservation Landscapes program is organized. We explore the links between outdoor recreation, climate change, and Pennsylvania’s geological history with DCNR’s Kristen Hand.

The last 400 years of Pennsylvania’s history are often covered in textbooks. But what about the last million years? Or 500 million years? The Pennsylvania we know today only exists because of a series of geologic events that occurred over this enormous time span.

Pennsylvania’s Grand Canyon.

“Pennsylvania is an amazing state because it is so ancient. And we can see so much of that time within the rock record,” said Kristen Hand, geoscientist for the Pennsylvania Geological Survey and DCNR Internal Lead for the Kittatinny Ridge Conservation Landscape. “We’re looking at 600 million year old rock record at the surface that you can see and interact with.”

Pennsylvania hasn’t always been full of woods, rivers, and gentle mountains. About 500 million years ago, the land that is now Pennsylvania was under water. This inland sea is responsible for many of the limestone deposits across the state. 

Over the millennia, there were 3 major mountain-building events, or “orogenies”, that shaped modern-day Pennsylvania. The third of these orogenies, the Alleghenian, occurred when the African continent collided with North America, forming the Appalachian mountains. When the mountain range was new, its peaks were taller than the Himalayas. Over the last 300 million years, the Appalachians have eroded into the rounded, forested mountains we see today. 

It’s geology that forms your sense of place.

Pennsylvania’s extensive geologic history helps draw millions of tourists looking for unique outdoor recreation experiences. Some of Pennsylvania’s greatest tourist attractions, like Ohiopyle Falls, Pine Creek Gorge (also known as “Pennyslvania’s Grand Canyon”), and the Susquahanna River all exist because of different geologic events. 

“It’s geology that forms your sense of place,” said Hand.

Views from the Kittatinny Ridge.

The Kittatinny Ridge, Hand’s focus in the Conservation Lanscapes program, is another special geologic feature.

“A lot of people are familiar with it because the Appalachian Trail runs on most of it. It’s significant not only for its recreation potential, but for its climate resiliency,” said Hand. “This area creates a flyway for us, and it’s a greenbelt that helps a lot of species as we move into climate change actually have a place where they can travel north… as temperatures become hotter and less stable.” 

As Pennsylvania reckons with its past of extraction, Hand believes that embracing natural assets and outdoor recreation will be the key to a more sustainable future. 

“It’s really great to se these towns become renewed and have people just put more and more energy into it,” she said “It’s really a great time to be in Pennsylvania.”