Towards the Unknown Region
The oldest rocks in the entire Rockies are exposed in Waterton-Glacier, Montana. In the Precambrian about 2.5 billion years ago an ocean developed in this area including sea-floor spreading. At such ridges lava constantly rises to the surface by spreading apart the ocean floor. Shock cooling of lava outflows on the seafloor due to contact with the seawater results in pillow formed lavas. Mighty layers of sediments accumulated on this volcanic sea-floor. In shallow lagoons stromatoliths built the first reefs on Earth. All this is preserved in the bedrock of this creek 2.5 billion years after this geological chapter was closed.
Pentax K2, Pentax 28mm, f/22, 4sec, Kodak Ektachrome E6, ISO 100, tripod