2G0 Bibliographical. Notices. 



water of existing seas is small, so that, unless the Jurassic seas were 

 differently constituted in this respect, the granules must have fallen 

 through an immense depth before a mere film could have become an 

 oolitic [grain. All evidence, such as that of reef-building corals &c, 

 goes to show that the oolitic seas were shallow, at least in England. 

 This chapter terminates with a table of the chief British strata, with 

 indications of the prevalent mineral character of the beds, &c. This 

 is a useful table, though the major divisions are very unequal. For 

 instance, the Trias, Permian, and Carboniferous are undivided, but 

 the Jurassic system is split up into Lias, Lower Oolites, Pelolithic, 

 and Psammolithic (part), an arrangement which few teachers would 

 recommend to their pupils. The fact is that Professor Seeley is a 

 law unto himself, a kind of geological nonconformist ; and in this 

 instance he seems to have taken a pleasure in defying the rules of the 

 International Geological Congress. 



Under the heading of " Petrology " he deals with the phenomena of 

 stratigraphy, and under that of "■The Physical and Mineral History 

 of Stratified Bocks " he again discusses the subject of sands, clays, 

 limestones, &c, not forgetting such concietionary bodies as flints. 

 A short chapter on coral-reefs closes this section of Physical 

 Geology. 



The two succeeding chapters deal with Physiographic Geolog} r , 

 including the study of coast-lines and their origin, and the general 

 features of scenery in their relation to geological phenomena : and 

 this again leads, in a third chapter (xi.), to that part of dynamic 

 geology which relates to the action of water in modelling the outer 

 crust of the earth. There is probably no more interesting branch 

 of geological science than this, certainly none more popular. Al- 

 though much is theoretical, especially when we come to deal with 

 subjects of past geographies, yet there is so much that is practical 

 about it, that almost every intelligent tourist can, up to a certain 

 point, make some portion of this branch of the science his own. 

 Professor Seeley gives a sketch of the physical history of the 

 British Islands and the Channel, and treats generally of the origin 

 of geographical features, such as islands, plains, valleys, &c. 



As the origin of lakes has given rise to much discussion in recent 

 years, it may not be without interest to note the views of an author 

 like Professor Seeley on the points involved: — (1) " Nearly all the 

 great lakes of the world," he says (p. 134), " owe their existence to 

 direct upheaval of the ocean floor." As instances he gives the great 

 Russian lakes Ladoga and Onega, which are merely prolongations 

 of the Gulf of Finland, leading northward to the White Sea, and are 

 the remains of a channel partly dried up. Consideration of the 

 lakes of Central Asia, many of which are salt from evaporation, 

 6erves to demonstrate how recent the last elevation of the country 

 from the sea has been. Lake Baikal is a freshwater lake, yet it 

 contains a large number of salt-water types of animals. Hence it 

 may be concluded that Lake Baikal was originally a portion of the 

 great Central-Asian sea, and was one of the deepest pools in its 

 bed, previous to the elevation of the mountain-axis of the old world. 



