For the succeeding several hundred million years the geologic history of
Glacier National Park is rather obscure, but additional Belt sediments
apparently were deposited before uplift of the area caused the sea to
withdraw. Following this event many feet of the younger Belt sediments
were removed by erosion. The sea probably returned and received more
sediments during much of the Paleozoic Era, although no trace of these
rocks has been found inside the park boundaries.