Barstow Formationとは 意味・読み方・使い方

The Barstow Formation is a series of limestones, conglomerates, sandstones, siltstones and shales exposed in the Mojave Desert near Barstow, California. It is early to middle Miocene (19.3 - 13.4 million years ago) in age, and lends its name to the Barstovian North American land mammal age (NALMA). The sediments are fluvial and lacustrine in origin except for nine layers of rhyolitic tuff. It is well known for its abundant vertebrate fossils including bones, teeth and footprints. The formation is also renowned for the fossiliferous concretions in its upper member, which contain three-dimensionally preserved arthropods.