The craton, or Precambrian basement was not highly deformed by the time of the early Paleozoic. This meant that if a eustatic sea level rise were high enough to cause the sea to cover the craton, most of Laurentia would be covered by shallow water (Lemon, 1993).

Painting by Michael Léveiller

According to the theories of continental drift and plate tectonics, the continents moved over time. North America, called Laurentia at the time, was located near the equator from the Cambrian to the Ordovician and traveled North later in the Paleozoic eventually arriving at our current position in the Northern Hemisphere. If Laurentia was equatorial and covered with water during the early Paleozoic, the waters composing the epeiric seas were subtropical to tropical. The seas were shallow and were thus easily infiltrated by the sun which helped create a warm environment in which organisms could live. The paleoclimate during the time was warmer than current temperatures inferring that the seas would be that much warmer (Wilde, 1991).

The image at left is a paleoreconstruction of the Champlain Sea.

This paleogeographic reconstruction of the Ottawa Embayment and surrounding regions during the early Blackriveran Stage is taken from Salad Hersi (1998). PTH stands for the paleotopographic high which existed east of the Ottawa Embayment thus hindering water circulation between the embayment and the eastern Québec basin. The Frontenac Trough connected the embayment with the Southern Appalachian Basin.

The glaciation affecting the Gatineaus occurred during the Cretaceous. At this point, Laurentia was in the Northern hemisphere and the Earth was cooler. Many organisms did not survive during this period as ice sheets covered most of Canada (Lemon, 1993).