[ 386 ] 



LII. Notices respecting Neiv Books. 



The Colorado-Plateau Region considered as a Field for Geological 

 Study. By Gr. K. Gilbert. 8vo pamphlet. Tuttle and Co.: New- 

 haven, Conn. 1876. 

 TF we proceed from the Mississippi valley across the plains to 

 -*• the westward, there are at first but few points of especial 

 interest to the geologist. 



The wide undulating plain-land, though necessarily elevated 

 above the sea-level, has suffered little in its upheaval ; and the 

 strata, though bent and wavy, present none of those great altera- 

 tions of structure and position that characterize the mountainous 

 backbone which borders the western edge of the plains and ex- 

 tends to the Pacific Ocean. 



Here violent destructive upturning^ of strata, complicated folds 

 and flexures, faults of great magnitude, and all the concomitant 

 circumstances of strata crushed, upheaved, and broken, give op- 

 portunity for study to the scientist and wondrous scenery for the 

 artist. 



But within this region lie a series of plateaus or high plains, 

 which, though seamed and fissured, altered and faulted, have ex- 

 perienced less violent alterations than its neighbouring ranges. To 

 this has been given the name of the Colorado-Plateau Province, 

 from the mighty river which, passing through it, has cut its way 

 through the successive layers, and formed, with its tributaries, a 

 group of formidable gorges or caiions, the origin of which it is the 

 purpose of this memoir briefly to elucidate. 



These plateaus are from 5000 to 11,000 feet above the sea-level, 

 terminated generally by high cliffs both in the canons and 

 elsewhere ; and the extreme dryness of the climate renders the 

 vegetation so scanty that the rock-masses are fully exposed to the 

 research of the scientific examiner. " There is no need to search 

 for exposure where every thing is exposed." Dr. Newberry, speak- 

 ing of one of the Southern Plateaus, says, " On our way to the 

 Moqui villages we passed through a region singularly favourable 

 for accurate geological investigation ; where there is no vegetation 

 to impede the view ; where the strata are entirely undisturbed, and 

 are cut by valleys of erosion in the wall-like sides of which every 

 inch of the series may be examined. 



"In this journey we ascended in the geological scale from the 

 summit of the Carboniferous to the base of the Cretaceous Series. 

 Of this interval there is no portion of which the exposures are 

 not as complete as could be desired." (G-eol. Ives's Exped. p. 77.) 

 The most arid, and at the same time obscure, portions are the 

 valleys between the ranges, " which are filled with quaternary 

 gravels and clays which hide all other beds ;" but in the great 

 river-channel the water has worn so vertically through the strata 

 that there is a full exposure of the material, the only drawback 

 being the narrowness and consequent darkness of many of these 



