fossil bed

A layer of identifiable fossiliferous material preserved in sedimentary rocks, fossil bed is also a common term for a fossil landscape buried by deposits and revealed only when denuded by wind, rain, or excavation. (The alternative term, exhumed landscape, is perhaps preferable.) The National Park System is rife with fossil bed sites: the John Day Fossil Beds in the John Day River basin of Oregon, noted for the discovery there of the small three-toed horse named Miohippus; the Agate Fossil Beds along the banks of the Niobrara River in Nebraska, an important source for 19.2-million-year-old mammal fossils; and the Florissant Fossil Beds just west of Pikes Peak in Colorado, where, 35 million years ago, an enormous volcanic eruption buried the valley and petrified huge redwood trees. The Ashfall Fossil Beds in northeastern Nebraska hold not just remnants but articulated remains with bones still joined together in their proper order—a product of the animals having been quickly buried in volcanic ash.

Kim Barnes