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The Ordovician in Manitoba, Canada

Ordovician in Manitoba map

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Ordovician Fossils

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Paleontology and geology

In the Ordovician, the basin to the southwest of Manitoba continued to deepen, while another basin began to form to the northeast around present-day Hudson Bay. As the basins dropped down, sediments eroded from the highlands were deposited as sandstones and shales along the shores and underwater. Toward the end of the period, reefs developed in the shallow waters teemed with corals, stromatoporoids, brachiopods, trilobites, gastropods, bryozoans, ostracods, and receptaculitids. Around Lake Winnipeg, there are abundant remains of soft-bodied seaweeds preserved as reddish-brown traces, as well as many invertebrates. Another area in southwestern Manitoba preserves spectacular fossils of eurypterids (sea scorpions), jellyfish, and the oldest horseshoe crabs. In some areas, the seas were so shallow that the water occasionally evaporated, leaving deposits of salt and gypsum. A few small hills along the shore of Hudson Bay were once part of an archipelago that extended into the sea during this period. The conglomerates, ripple marks, and orientation of the cephalopod fragments in these rocks indicate a strong current moved along the coast.

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