Wiktionary
n. (context paleontology English) A sedimentary deposit that exhibits extraordinary fossil richness or completeness.
Wikipedia
A Lagerstätte (, from Lager 'storage, lair' Stätte 'place'; plural Lagerstätten) is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus delaying decomposition. Lagerstätten span geological time from the Neoproterozoic era to the present. Worldwide, some of the best examples of near-perfect fossilization are the Cambrian Maotianshan shales and Burgess Shale, the Devonian Hunsrück Slates and Gogo Formation, the Carboniferous Mazon Creek, the Jurassic Solnhofen limestone, and the Cretaceous Santana and Yixian formations.