undifferentiated rock units

Paleontology and geology

Mainland Nunavut was above sea level during the Cretaceous, while a shallow basin covered several islands in the Arctic Archipelago. In the Early Cretaceous, huge deposits of lava formed on some of the northern islands as the Arctic Ocean opened up. And by the end of the period, Baffin Bay started to form as Greenland rotated counterclockwise and collided with some of these islands, folding, faulting, and pushing up rocks in this area. Sandstones, siltstones, and shales deposited in marine and freshwater environments from this period record some of the plants and animals that lived in this territory. In addition to fossils of seed-bearing and flowering plants, there are also ammonites, bivalves, and dinoflagellates, as well as many different vertebrates, including several species of fish, plesiosaurs, champsosaurs, turtles, the aquatic, toothed bird Hesperornis, and a few hadrosaur bones.