Sullivan County contains 478 square miles, considered by the Federal government as “Entirely Rural”. Most of the county is mountains and valleys, with the Loyalsock and Little Loyalsock creeks meandering throughout.
One third of the county’s 305,920 acres are state owned as State Game Lands, State Forest, or State Parks: World’s End near Forksville, and Ricketts Glen, near Red Rock. Hunter’s Lake, near Eagles Mere, and the 1500 acre tract that surrounds it, is owned by the Pennsylvania Fish Commission.
Sullivan County was covered by a shallow sea during the Paleozoic Era (600 to 230 million years ago). Sand and silty claylike sediment was deposited which formed gray and red shale commonly found here today.
Some of the shale deposits are fossil bearing, especially those laid down during the Devonian period. Brachoids, glass sponges, chrinoids, and graptolites are common in
gray shale. Lungfish burrows are found in a roadside outcropping of red shale between Forksville and World’s End State Park.
Lopez and Mildred areas have large coal deposits formed during the Paleozoic Era. Fossilized ferns and shells are often found in the coal and dark shale deposits surrounding these communities.
At the close of the Paleozoic Era sedimentary layers were compacted and raised above sea level, forming the bedrock of Sullivan County. Bedrock is visible in many
places throughout the county, including the Sullivan County School grounds in Laporte.
Two glacial periods covered what was to be Sullivan County with ice during the Pleistocene Era one million years ago. Glaciers remained in the region up to 12,000 to
15,000 years ago. Glaciers eroded the ancestral Appalachians to the familiar mountains and valleys of today, but in Sullivan County pre-ice ridges remain. This accounts for the somewhat rugged nature of the mountains here.
Combined with altitude, these conditions have allowed alpine plants to thrive on the higher peaks. Glacial mountaintop bogs are fairly common, and in at least two
locations in the county there are small ice caves which hold ice formations throughout the summer.
