Rock City State Forest

The area around "Little Rock City" tells the geologic history of Western New York. The conglomerate rock is younger and very different than the bedrock in Western New York. During the late Devonian period (circa 370 million years ago) this area was on the shore of an ancient sea. Here, streams flowing from the Acadian Mountains in what is now New England and New Jersey mixed with the sea. Sediment was transported by the streams and deposited by the sea currents. Occasionally, a red Jasper stone can be found among the conglomerate. According to the Theory of Continental Drift, all of North America was rotated 450 degrees clockwise during the Devonian period; meaning Lake Superior would have been due northwest of this area. This would allow sea currents to transport the Jasper pebbles into this area.

Over time the conglomerate was buried under thousands of feet of sedimentary rock, similar to that of Allegany State Park in Pennsylvania. The overlying rock was then eroded during the Alleghanian Orogeny, or mountain building, which uplifted Eastern North America (circa 290 million years ago). It was this event, resulting from the collision of North America and Africa, which formed the supercontinent Pangaea. Over time, erosion released pressure allowing the conglomerate to expand and crack. These cracks, called joints, along with joints formed by horizontal compression during orogeny itself, resulted in two sets of intersecting perpendicular lines which, through weathering, widened to become the pathways separating the blocks.

Info from the NYS DEC

FLT Map M2