Paleontology and geology Early in the Ordovician, shallow marine
environments covered much of Georgia. However, toward the end of
the Ordovician, the ancient continent of Laurentia collided with
an oceanic plate. This collision caused the first of three
episodes of mountain building that contributed to the formation
of the Appalachians. Large amounts of sediment eroding from the
mountains were carried to the sea and formed extensive tidal
flats. These were later replaced by estuaries as more fresh
water flowed into the seaway. Typical Ordovician fossils include
brachiopods and bivalves, as well as traces of burrows, most
likely formed by trilobites.