More than 700 million years elapsed between intrusion of the black dikes and deposition of the first Paleozoic sedimentary rocks. The Precambrian rocks were uplifted during this gap in the geologic record known as an unconformity; exposed to erosion they were gradually worn to a nearly featureless plain, perhaps resembling the vast flat areas in which similar Precambrian rocks are now exposed in central and eastern Canada. At the close of Precambrian time, about 600 million years ago, the plain slowly subsided and the site of the future Teton Range disappeared beneath shallow seas that were to wash across it intermittently for the next 500 million years.