undifferentiated rock units

Paleontology and geology

In the Early Carboniferous, the shallow seas that covered much of Manitoba in the Devonian began to retreat. The limestones that formed on the reefs in the shallow seas were replaced by salt and gypsum, deposits that formed as sea water evaporated. Eventually, these extremely shallow deposits were replaced by shoreline and beach deposits as more areas were left above sea level. As more and more land was exposed through the rest of the period, erosion continued to remove any sediments on land. While some of the marine, lagoon, and beach deposits have been eroded away as well, others have been buried by younger rocks in the southwestern portion of the province. A few small outcrops may be found on more detailed maps.