The Cripple Creek gold deposits, discovered in 1891, were investigated by Messrs. Cross and Penrose, of the United States Geological Survey, in 1894. The present reexamination was requested by citizens of Colorado, and . has been carried out under the financial cooperation of the State with the Federal Survey. It has involved complete revision of the topographic map of the district used as a base by Cross and Penrose, the running of a line of accurate levels from Colorado Springs to Cripple Creek, remapping of the geology, and a thorough study of the extensive mine workings opened during the past ten years. Due acknowledgment is made, of the cordial assistance rendered by mining men, and a list is given of the important publications concerning the geology or mines of the district.