undifferentiated rock units

Paleontology and geology

The mainland of Nunavut was exposed above sea level during the Silurian, but the Arctic islands were covered by shallow to deep seas. Salt and gypsum deposits accumulated in areas near the coast when seawater evaporated. The shallow to deep areas farther from land were home to a great variety of invertebrates, some of which built up reefs. There were trilobites, brachiopods, bryozoans, crinoids, sponges, corals, and graptolites. Many different fish, such as thelodonts (small jawless fish with tiny scales) and placoderms (armored jawed fish), swam in these waters as well. In the Late Silurian, several islands from out in the ocean collided with northern Ellesmere Island. This collision folded, faulted, and pushed up rocks in this area.