      Agate Fossil Beds National Monument      National Monument
Nebraska  Nature & Science  The Agate Fossil Hills under blue
skies.  The Agate Fossil Hills  Agate Fossil Beds National
Monument is nestled in the Niobrara River Valley in Nebraska 65
miles [110 km] east-southeast of its headwaters in the Hat Creek
Breaks of Wyoming. The park preserves a unique unglaciated area
of the High Plains. Wetlands stretch out from the river and meet
terraces that lead to the breaks and buttes. The buttes contain
important information about the life of mammals in the Miocene
Era, some 20 million years ago.  During the Miocene the land now
known as Agate was a grass savanna comparable to today's
Serengeti Plains in Africa. Twenty million years ago animals
such as the Dinohyus (giant pig-like animal), Stenomylus (small
gazelle-camel), and Menoceras (short rhinoceros) roamed the
plains. There were also carnivorous beardogs wandering around,
and the land beaver Paleocastor dug spiral burrows that remain
as today's trace fos