The Devonian in Ontario, Canada

Paleontology and geology

For much of the Devonian, Ontario was above sea level and exposed to erosion. In the Late Devonian, shallow seas flooded the middle of the continent, covering most of the province. Most of the limestones, sandstones, and shales deposited in these waters have been eroded away, but exposures can be found in the northwest and central parts of the province. Southeastern Ontario was above sea level in the Early Devonian, but the seas quickly returned and remained throughout the rest of the period. Marine sedimentary rocks in the south contain abundant fossils of the diverse marine organisms that lived here, including corals, brachiopods, bryozoans, cephalopods, gastropods, crinoids, and trilobites. In deeper waters, organic material accumulated on the muddy sea floor in stagnant, low-oxygen waters. These sediments are now preserved as dark-colored shales, and one outcrop of this black shale produced a rare discovery: a worm preserved in three dimensions in the mineral pyrite.