The Nacimiento uplift in the west edge of the Rios Gallina and Chama Watersheds, and volcanic activity and the San Juan Uplift to the north and east formed the Chama Platform and eventually the “glacial flume”.
Glaciation may have covered a broad area initially, perhaps even over the Continental Divide to the west.
As glaciation and erosion focused into the Rio Chama Watershed, it repeatedly stripped away formation after formation of oil and gas-bearing strata still be found in much of the San Juan “Basin”.
Flushing of any remaining formations occurred with each glacial melt and even now with snow-melt and rain.