Jacksville Esker and Glacial Deposits


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Wide2.jpgAlthough both parks are the result of glaciation of the region, neither contains easily observable, characteristic glacial deposits. The closest glacial feature of note is the Jacksville Esker, 2½ miles north of Moraine State Park. An esker forms when meltwater drains into a glacier through fractures and flows through ice tunnels at the base of the glacier. Sand and gravel deposited along the tunnel floor remain as an elongate, often sinuous, ridge standing above ground level when the ice melts. Esker sediment is deposited in a channel confined within the ice, rather than in a channel eroded into the ground. The 6-mile-long Jacksville Esker (also known locally as the West Liberty Hogback and Miller Esker), formed during the last glaciation, about 23,000 years ago, and is the best preserved esker in Pennsylvania. The portion of the esker visible from the marker is owned by the Western Pennsylvania Conservancy and open to the public. Stay near the tree line as you walk to the top of the esker to get a feel for its size.

 

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Swope Road Sediments

Swope Road cuts through the esker, exposing the sediments (N). The gravel and cobbles range from local sedimentary bedrock to metamorphic and igneous rocks transported by glaciers from Canada. Because sand and gravel are valuable sources of roadbase and concrete aggregate, and other construction materials, parts of this esker and other glacial deposits are disappearing rapidly through economic exploitation. 

 

 

 

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Esker Bedding and Faults

If a section across the esker were exposed, the layers of sand and gravel would be arranged in a domed-shape. The layers along the sides of the esker would be faulted because of the removal of the supporting tunnel ice walls when the glacier melted. 

 

 

 

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Kettle

Also visible from the top of the esker on Swope Road is a kettle.