Glacial River Warren, also known as River Warren, was a prehistoric river that drained Lake Agassiz in central North America between about 13,500 and 10,650 BP calibrated (11,700 and 9,400 14C uncalibrated) years ago.[1] A part of the uppermost portion of the former river channel was designated a National Natural Landmark in 1966.[2]
Year designated: 1966