1. Geologic map of the eastern half ot the Vail 30ʹ x 60ʹ quadrangle, Eagle, Summit, and Grand Counties, Colorado [cartographic material] Yale Public content 2011. 2012-01-10T18:50:01Z. 2015-10-09T14:33:25Z. Kellogg, Karl S. U.S. Dept. of the Interior, U.S. Geological Survey ; Denver, CO : U.S. Geological Survey. English. Public. Colorado, Eagle County, Summit County, and Grand County.