Weathering is the breakdown of rock into small particles and can occur through chemical or physical mechanisms. Erosion is the transport of these particles by running water or landslides. Running water will typically seek the path of least resistance, cutting through softer, finer grained rock layers, while avoiding more resistant layers. This is evidenced by the fact that the floor of Cold Canyon lies in the midst of a fine grained mudstone layer, while the canyon walls consist of more resistant sandstone layers. The erosion that created Cold Canyon continues today both on a small scale, through the chemical breakdown of rock by air and rain, and on a larger scale by physical mechanisms such as landslides.
Landslides are common on the steep walls of Cold Canyon.
In 1995, a large landslide came down the eastern wall, toppling trees and piling soil and rocks along the streambank. The evidence of this slide can easily be seen along the trail, near the mouth of the canyon. More gradual erosive processes are also currently taking place. The creek actively erodes its channel, especially during winter floods, and Cold Canyon gets slightly deeper every day. The rounded boulders in the creek bed, smoothed by the scouring action of sediments transported by the stream, attest to this on-going erosion.