As a selling point on school tours, a staple in every pre-frosh publication, and a popular spot during Ithaca’s few warm months, the gorges are a major part of Cornell culture. While “Ithaca is gorges” t-shirts are seen by the dozens daily, many students are unaware of how these beautiful waterfalls came to be.

According to Earth and Atmospheric Sciences Professor Rick Allmendinger, processes during and after the last ice age are to credit for the formation of the gorges. Within the last few million years, there have been several pulses of glaciations.

According to The Paleontological Research Institution, the Finger Lakes were initially “river valleys with small streams flowing in from the east and west.” During the last pulse, about 25,000 years ago, Ithaca was covered by glacial ice; glacial erosion produced large amounts of sediment that filled these valleys.

Ithaca is located near the present day St. Lawrence and Susquehanna drainage divide and had many pre-glacial paths of drainage leading to both rivers. Essentially, the most recent glaciations changed the drainage patterns by moving debris into valleys and formed new ones; waterfalls were formed at the intersection of new and old valleys.

Materials eroded by the streams were discharged in deltas at the creeks’ mouths. Still today, the water erodes the gravel and bedrock which form the gorges. Erosion molds the rock and pebbles. The rate of erosion is highly dependent on the weather; for example, rainstorms and melting snow cause increased erosion.

On North campus, Risley Hall and Helen Newman Hall were built atop an old, sand and gravel-filled pre-glacial valley. This is the same pre-glacial valley that one crosses when going from Fall Creek to Sibley Hall. Crossing Fall Creek on Thurston Avenue, one can actually notice the meeting of the two gorges, as one is bedrock and the other is gravel.

These glaciers are indirectly responsible for the unique topography of Cornell campus. As the ice cap melted back northward, a high level "proto-Cayuga" Lake formed between the glacier front and the higher topography to the south. At the high point (960 ft) about 15,000 years ago, the entire Cornell campus was under water. For example, west campus is relatively level, a step up Libe slope, then the Arts Quad is flat. The same pattern follows when one climbs the hill in front of Rockefeller to get to the Ag Quad.

As the proto-Cayuga lake level fell, materials eroded by the streams were discharged in deltas at the point where the creek entered the lake, leaving “hanging deltas. The final cutting of the gorges accompanied the falling of the lake level. Today, running water and the sediment it carries as well as winter freezing and thawing continue to erode the gravel and bedrock which form the gorges. Most erosion today probably occurs during heavy rainstorms and the melting of spring snow.