The rocks found at Hoxie Gorge belong to the Geneseo Formation of the Upper Devonian Series. The rocks are shales but become coarser in texture as time progressed and the younger Sherburne and Ithaca formations were deposited. They all contain marine fossils as well as increasing quantities of land plants. Moreover, there is abundant evidence of these sediments' having been deposited as a delta. The position of the actual gorge at Hoxie Gorge on the landscape can and has often been explained by joint pattern known to exist in the area.
Joints are fractures which are found regularly repeated in the bedrock.
Because joints are weaknesses in the rock, streamflow is accentuated along joint traces at the surface. The concentration of rain runoff has downcut along the joint set to be what we know as Hoxie Gorge today. Rocks are not everywhere uniform and the stresses applied to form joints are dispersed according to the characteristics of the rock. Fossils of Hoxie Gorge Fossils are not known to be in abundance in the rocks of Hoxie Gorge, not in numbers of individuals or in variety. Fossils have long fascinated everyone, from school children to senior citizens, and when we see them in the rocks, the foremost concern is what they are.