The rocks in the Cold River Corridor tell a fascinating story of three distinct geological periods. The first period of mountain building occurred about 375 million years ago. The second occurred when magma was injected into the pre-existing mountain rocks. These first two chapters of the Cold River’s geologic history built the bedrock of the river’s course. The third period played off these two by altering the surficial geology of the river through the glaciers that reached down from Canada and scoured the terrain. Melt water from these glaciers shaped the land surface both by eroding it and by depositing vast quantities of materials- sands, silts and large glacial erratics.

​The 1983 New England Rivers Center New Hampshire River Protection and Energy Development Final Report noted the high significance of the geologic/natural features of the Cold River based on a state-wide analysis of river resource values