The elevation of the Rocky Mountains was during Peleg's tectonics, 101 years after Noah's flood. It occurs in the narrative of evolution as a way to stretch out the timescale into millions of years.
Elevation of Rocky Mountains
Uplift in Appalachian Geosyncline
"Uplift in Appalachian geosyncline" took place when the tectonic plates formed in the time of Peleg. This was 101 years after Noah's flood.