undifferentiated rock units

Paleontology and geology

Through the Triassic, most of Northwest Territories was above sea level and exposed to erosion. In the north, sediments eroding off the land traveled along rivers, through deltas, and out into a basin that formed over a few of the islands in the Arctic Archipelago. In the west, sediments were carried out onto the continental shelf. Sandstones, siltstones, shales and limestones deposited in these environments contain trace fossils, crinoids, and bivalves, as well as pollen and spores from land plants. Many of the deposits from this period have been removed by erosion, but there are deposits below the surface in the Arctic islands and southwestern mountains. A few small exposures can be found in the northernmost islands as well.