556 Notices respecting New Books. 



The broadly read history of the region shows that after the in- 

 calculably old Archaean rocks were covered by Silurian and Devonian 

 strata, these also were disturbed, elevated, worn down, and then 

 covered by the Carboniferous beds in a moderately deep sea ; and, 

 after an uplift and denudation, sinking clown, they were covered 

 with Permian and Mesozoic strata, in shallow seas, with continually 

 sinking sea-bed, and with exceedingly regular horizontality, until 

 in that long succession of ages from 12,000 to 16,000 feet of strata 

 were accumulated over the entire Plateau Province. Near the end 

 of the Cretaceous period there was a change : the ocean-waters were 

 restricted, the sea became brackish, and parts of the land were 

 raised and denuded. Again submerged, they were coated uncon- 

 formably with the Eocene deposits of a great lake nearly correspond- 

 ing in extent with the Southern Plateau Province. In the Middle 

 Eocene Period the western portion of the continent began to rise ; 

 and, in alternating periods of activity and repose, continued to be 

 raised until a recent epoch. An outlet of the great Eocene lake 

 was a river which originated the Colorado, perhaps in late Miocene 

 times ; and this slowly won its way over and through the Eocene and 

 all the older strata, cutting through them, as the rising of the land 

 slowly brought them within its influence, probably with intervals 

 of rest, as marked by the terraces. Lateral streams and the com- 

 bined influence of climatic agencies have eroded the wide stretch- 

 ing plateaus, the channels being deepened and deepened by the 

 corrasive action of the water carrying sand and stones as mechani- 

 cally erosive agents, whilst rain was too rare to destroy the sharp 

 angles of the banks. The narrow but great Canon is of relatively 

 recent manufacture ; and how far the drainage-system can yet be 

 extended and deepened (to the possible " base-level of erosion") is 

 an interesting subject of inquiry. 



The details of geology and of physical geography are conveyed in 

 the author's readable account of jonrneyings, observations, enthu- 

 siastic admiration of the unsurpassable phenomena of lights and 

 shades, colours and cloud-scenery, sunshine and twilight, among 

 the Titanic architecture of cliff and mountain. The illustrations, 

 both as drawings of scenery, often beautifully coloured*, and of 

 contoured geological maps, are such as only the highest scientific 

 liberality could place before the world ; and the generosity of the 

 United-States Government in freely supplying this and other mag- 

 nificent monographs to Scientific Societies and working Naturalists 

 abroad and at home is not only worthy of all praise, and gratefully 

 acknowledged, but puts to shame the niggard ways of our Imperial 

 Government, hesitating to produce, and refusing to disperse liberally 

 scientific works in Britain. 



* Both atlas and text are enriched with some of the best work of Mr. 

 W. II. Holmes, whose masterly and faithful rendering of geological 

 scenery, both as landscapes and panoramas, is unrivalled. 



