Map Courtesy of Pennsylvania Geological Survey
Visit Butler County Pennsylvania!
By Jeffrey Calta
Butler County, PA has many interesting historical sites that are only a short drive away for residents of Western PA. In addition to the many cultural sites, the county also has numerous geologic features left over from the ice sheet (glacier) that once covered its northwestern section. There are two locations in particular that were formed by the glacier and offer an ideal day trip for exploring Butler County pre-history.
Location #1 - Ancient Spillway of Lake Edmund
and Lake Watts
The southward advance of the last glaciation (known as the Wisconsian ice sheet) ended on a line southwest to northeast in Butler County very close to the present town of Slippery Rock. Before the glacier appeared, the streams and rivers in northern Butler County flowed toward the Lake Erie Basin. Once the glacier arrived approximately 20000 years ago, the ice prevented the waterways from draining and two lakes were formed as surface water and glacial melt water began to accumulate. Lake Edmund occupied much of northern Butler County and Lake Watts was located where modern Lake Arthur is now. As lake water levels grew higher, the lakes merged near the town of West Sunbury. A spillway opened near Queen Junction and the lakes began to empty southward toward Connoquenessing Creek. The spillway was active for thousands of years and the water cut a gorge that still exists today and is used by the Bessemer and Lake Erie railroad for a rail corridor. Follow Mahood Road westward for 6.8 miles from Route 38 until you arrive at the bridge that crosses the Bessemer & Lake Erie railroad line just south of Queen Junction. An alternate route is to follow Mahood Road eastward for 2.4 miles from Unionville on Route 8. Water flow from the lakes would have been from the north heading south. Stop to look and ponder the waterfall and immense water flow that would have been present in this spillway many thousands of years ago.
Location #2 - Jacksville Esker Near West Liberty
An esker is a geologic formation created at the very edge of a melting glacier. Eskers are large deposits of sand and gravel that occur as the glacier melts and begins to retreat. They form as glacial melt water carves tunnels in the ice and fills them with accumulated sediment and gravel that the glacier scooped up on its travels southward. Once the ice is gone, the gravel and sand are left in snake-like hills that wind through the country side. The Jacksville Esker, also known as the West Liberty Hogback, is considered the best-preserved esker in Pennsylvania. The size of the esker is impressive. It stands 50-60 feet high, with a length of 600 yards and was once much longer. Many eskers in PA were mined for their valuable sand and gravel including Jacksville. Part of the Jacksville Esker was saved from destruction when the Western PA Conservancy purchased the site. The public is allowed to climb and walk the esker. Follow the signs at the parking lot and stay on the Conservancy’s short trail to the top of the esker. The esker is located on West Liberty Road several miles west of the town of West Liberty. The entrance to the esker parking lot is a very short distance on the right once you have passed the Mt. Union Road intersection with West Liberty Road.
Special thanks to Gary Fleeger for providing source material for this article.
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