Определение agate fossil beds national monument в Английский Язык Английский Язык словарь
Natural "depository" of an extinct animal community on the Niobrara River, northwestern Nebraska, U.S. The beds, laid down as sedimentary deposits 20 million years ago, bear the remains of prehistoric mammals. Discovered 1878, the site was named for its proximity to rock formations containing agates. A national monument since 1965, it covers 2,269 acres (918 hectares)