This paleontological site represents the nation’s only recorded discovery of a nursery herd of Columbian mammoths. Reaching 4 m (13 ft) at the shoulders and 22,000 lb in weight, research has indicated that between 65,000 and 72,000 years ago, a nursery herd of at least 19 mammoths were trapped and drowned by rapidly rising flood waters from the Bosque River.