Reviews and Notices of Booh. 215 



tory into the Pacific. The physical features of t^ie region are re- 

 markable, presenting a series of deep ravines or '' canons" in 

 which the Colorado and its tributaries flow at depths amounting 

 in some cases to two or three thousand feet below the level of 

 the neighbouring table-lands. The scenery presented in these 

 deep cuts is of the most magnificent description, apalling the vis- 

 itor with its gloomy grandeur. In the lofty precipices the whole 

 palaeozoic series of rocks may be seen in regular and undisturbed 

 succession, and resting on older metamorphic rocks ; while in the 

 higher table-lands cretaceous and triassic rocks appear, the 

 whole apparently constituting a continuous undisturbed series. 

 Dr. Newberry, the geokgist of the expedition, has well availed 

 himself of these magnificent exposures. He attributes the pre- 

 sent irregular features of the country entirely to aqueous erosion, 

 and this by running water. It is indeed the long prevalence of 

 river action in an undisturbed country that can alone produce 

 such efi'ects. 



The survey of Maine, at the opposite extremity of the Union, 

 from the Colorado river, was commenced last year by Mr. Hitch- 

 cock, and his report shows a most praiseworthy diligence, 

 and an excellent combination of effort with others working in 

 neighbouring fields, along with great capacity for such work. 

 The observations made and fossils collected enable us for the first 

 time to form just ideas of the parallelism of large portions of the 

 rocks of Maine with those of New York, Canada and Nova Sco- 

 tia. The lower silurian rocks are represented by clay slates, 

 holding a few fossils regarded as primordial in their type. 

 Other deposits occurring in several places are regarded as upper 

 silurian, and correspond very nearly with the " Arisiag series " of 

 Nova Scotia. There are extensive deposits of Devonian rocks, in 

 one member of which, exposed at Perry, we have three remark- 

 able plant-beds, some of the fossils of which have been noticed in 

 this journal. The drift deposits have also been carefully sketch- 

 ed, and with the aid of Mr. Fowler of Portland, a list of these fos- 

 sils has been prepared, and comparisons instituted between them 

 and those of the similar deposits in Canada, with which they cor- 

 respond very closely in their arrangement and fauna. The indica- 

 tions are those of a marine fauna similar to those of the present 

 coast, but with a prevalence of more northern forms indicating a 

 somewhat colder climate. J. w. d. 



