when do the first coral reefs appear in the fossil record
Coral Although corals first appeared in the Cambrian period,[28] some 542Â million years ago, fossils are extremely rare until the Ordovician period, 100 million years later, when rugose and tabulate corals became widespread. Paleozoic corals often contained numerous endobiotic symbionts.[29][30]
Paris Peace Accords
Buddhism in Southeast Asia
Backshore Sediments in this area are well-sorted and well-rounded. Its grain sizes are mainly coarse sand and medium sand, which are larger than that in littoral barrier dune.The sedimentary structures include parallel bedding and low-angle cross-bedding.