[ 551 ] 



LXII. Notices respecting New Boohs. 



Department of the Interior. Monographs of the United- States Geo- 

 logical Survey. Vol. II. 4to. Washington, 1882. 



United States Geological Survey. J. W. Powell, Director. — Tertiary 

 History of the Grand Canon District. 4to, 264 pages, with wood- 

 cuts and 42 plates ; and folio Atlas of 23 plates of maps and 

 views. By Clarence Dutton, Captain of Ordnance, U.S.A. 

 Washington, 1882. 



THE subject of this masterly work may be regarded as a history 

 of Erosion on a grand scale, as shown by the physical features 

 of the Grand-Canon district. Erosion depends upon climatal con- 

 ditions, the local characters of the ]and, and the progressive eleva- 

 tion of the region affected. In working out this history the author 

 has endeavoured to correlate all the conditions, processes, and 

 events, and has clearly indicated the progressive evolution of the 

 physical features of this wonderful region, with their origin and 

 changes, and the existing results of the order of events. The 

 district treated of, chiefly in North-western Arizona, but extending 

 northward into Utah, is about 180 miles from N.W. to S.E., and 

 125 miles N.E. to S.W., and has between 13,000 and 16,000 square 

 miles. The " Colorado Eiver of the West " traverses it in an 

 average W.S.W. tortuous course, along the Glen Canon, Marble 

 Canon, and Grand Canon. The last name, however, has been 

 misapplied to the gorges of other rivers. The deep-cut channel is 

 bordered by high, extensive, and successive plateaus, conterminous 

 with strong escarpments of great geological formations. Those 

 on the north comprise the Eocene, Cretaceous, Jurassic, Triassic, 

 Permian, and Carboniferous rocks ; and the last is continued as 

 the surface-ground on the south side of the river for at least 

 130 miles, with an extent of many thousand square miles. These 

 plateaus, channelled and scored with drainage-lines, are modified 

 according to the nature of the strata, and at places by the occurrence 

 of igneous rocks. 



The Eocene strata form the Markagunt and Paunsagunt Plateaus 

 (nearly 11,000 feet above the sea), overlooking the Grand Canon 

 from the north, at a distance of some 80 miles. Their escarpment, 

 800 feet deep, is marvellously sculptured and coloured : obelisks 

 and pilasters form a gigantic ruined colonnade of pale and rich red 

 tints, " beautiful beyond description." These are but the Lower- 

 Eocene lake-marls, of the same age as those of the Uinta Moun- 

 tains (Green Eiver, Bitter Creek, White and Uinta Eivers). Still 

 further north Middle and Upper Eocenes occur, making a w 7 hole 

 thickness of 5000 feet, but the Lower Eocene only seems to have 

 been at any time present at the plateaus above mentioned, with 

 their intrusive trachytes and basalts. Probably the great Tertiary 

 lake began here to be dried up, though persisting further north- 

 ward in later Eocene times. 



