undifferentiated rock units

Paleontology and geology

Marine waters spread over much of Northwest Territories through the Ordovician, while the eastern half of the territory was above sea level and exposed to erosion. Sediments from land were deposited over the continental shelf and slope that covered the rest of the territory. The shallow to deep waters were home to many invertebrates, such as brachiopods, trilobites, bryozoans, conodonts, and ostracods. Their fossils are preserved in some of the sandstones, shales, and limestones that formed in these seas. Many of the rocks from this period have been eroded or covered by younger rocks, but a few exposures can be found in the north and southwest. Additional exposures may be included in the undifferentiated Paleozoic rocks on this map.