WHITHER THE RIO GRANDE RIFT?

The northern terminus of the Rio Grande Rift has puzzled many. Some suggest it ends at Leadville on the northern end of the Upper Arkansas Valley, some suggest it continues northward to Kremmling, some suggest it continues into North Park, some even suggest it continues on to Yellowstone. Others proposed that the Rift wraps around the Aspen Anomaly, or continues out through northwestern Colorado.

This study proposes that the Rio Grande Rift and its extension form the eastern and northern boundary of the Colorado Plateau. The northeastern corner of the structural Plateau is located just south of Steamboat Springs, Colorado. The northern boundary of the Plateau is defined by a broad zone experiencing north-northeast extension which is defined by a distributed zone of Late Cenozoic faulting, numerous stress indicators, and basaltic volcanism. The entire system can be explained by a clockwise rotation of the Colorado Plateau away from its northeastern corner.