Merrill Linn Trail (5)
Vernal pool, Bald Eagle State Forest, Union County, along the Merrill Linn Trail.
According to the Merrill W. Linn Land and Waterways Conservancy, the pools are pingo scars—water-filled depressions that formed during the last ice age when subsurface ice rose up through the permafrost and melted as the climate warmed.
Similar pingo scars are found farther south at the Halfway Run Natural Area.
Merrill Linn Trail (5)
Vernal pool, Bald Eagle State Forest, Union County, along the Merrill Linn Trail.
According to the Merrill W. Linn Land and Waterways Conservancy, the pools are pingo scars—water-filled depressions that formed during the last ice age when subsurface ice rose up through the permafrost and melted as the climate warmed.
Similar pingo scars are found farther south at the Halfway Run Natural Area.