This orogeny is the main uplift forming the Rocky Mountains which occurred relatively late in geologic time. The sandstone dikes contain fragments from the Permian-Pennsylvanian Fountain Formation, indicating that at least this formation was present at the time of intrusion. On a geologic time scale this represents a period of at least 250 million years during which the Sawatch sandstone remained uncemented. This seems especially unusual since just above the Sawatch are several carbonate layers that could provide an abundant source of cement for the Sawatch. If, as field evidence indicates, intrusion took place during the Laramide Orogeny, the Sawatch sandstone would have had to remain uncemented for more than 400 million years.
Intrusive sandstone dikes in granite.
Harms , John C. 1965. Sandstone dikes in relation to Laramide faults and stress distribution in the southern Front Range, Colorado. Hayashi , Tadaichi. Newsom , F.J. 1903. Peterson , Gary L. 1968.