undifferentiated rock units

Paleontology and geology

In the Devonian, northern and central Quebec were above sea level and exposed to erosion. Collisions to the south and east of the province continued to add new pieces of land to the continent. These collisions created faults and brought magma up to the surface, forming the igneous rocks exposed in southeastern Quebec. This part of the province was still covered by a shallow sea, as evidenced by deposits of limestone, sandstone, and shale. The most famous deposits are the shales and sandstones at Miguasha. This area has been designated a UNESCO World Heritage Site for its abundant, diverse, and well-preserved fossils of early fish, including the lobe-finned fishes that gave rise to tetrapods. Two fossils in particular from this locality, Eusthenopteron and Elpistostege, have been important for understanding how vertebrates moved onto land. Other fish fossils include early ray-finned fishes, placoderms, lungfish, acanthodians, and agnathans. Although not as common, eurypterids and other arthropods, plants, and trace fossils have also been found.

By the end of the Devonian, southeastern Quebec was uplifted and the shallow sea drained away. However, in the middle of Laurentia, the shallow sea which had retreated for most of the period, returned for a short time in the Late Devonian, leaving the sandstones that outcrop in a small area of western Quebec.