Geologic and geophysical investigations of the Loveland Basin landslide, which formed at the cut for the east portal of the Straight Creek tunnel, were made by the U.S. Geological Survey in cooperation with the U.S. Bureau of Public Road and the Colorado Department of Highways. The investigations indicate that the slide has a probable minimum volume of 500,000 cubic yards weighing 1,000,000 tons and probable maximum volume of 770,000 cubic yards weighing 1,600,000 tons.