268 Revieivs — Ansted's Physical Geography. 



readers are left to evolve theories for themselves as to our planet's 

 condition when the, perhaps, altered rocks of the remote interior, 

 or even at a depth of two thousand miles, were, it may be, formed 

 at the surface. 



Chapter third is geological, dealing with the succession of rocks 

 and metamorphosis, setting forth with regard to the latter that "it 

 is certainly by, and with water, that all essential change must be 



traced Water has compacted the loose particles ; water has 



opened large cavities ; water has filled them with quartz and other 

 crystals ; and water has carried in the metals. A little heat would 

 have caused other combinations." 



To currents of heated water and electric currents all the trans- 

 formation and metamorphosis of the richest metalliferous rocks of 

 countries where mining is carried on in slate are attributed ; while 

 nervous energy in the animal system is said to be represented in the 

 globe by ciu^rents of earth-magnetism mysteriously obtained from 

 the sun, and vital heat by the higher and equable temperature at 

 moderate depths. 



In part the second, under the heading Eabth, we have an able 

 but short summary of the distribution of the land, and its forms, its 

 mountain chains, hills and valleys, plateaux and low plains. This 

 portion of the work, the smallest but one, treats essentially of the 

 geography called physical, and is pregnant with matter so interest- 

 ing to the student of this science that its condensation will be re- 

 gTetted though it consists mainly of statistics, so to speak, and 

 touches lightly upon theories relative to the causes which may have 

 governed or produced the present arrangement of the great physical 

 features of the globe. Denudation is said to have played an im- 

 portant part in all the phenomena of Switzerland and the Tyrol ; 

 but its effect in forming the high detached mountains of the Alps 

 is not discussed, nor is its powerful agency in producmg mountain 

 forms prominently put forward. 



There are said to be valleys of fracture or fault, and valleys of 

 erosion, — mountain gorges being referred to the former, but no 

 examples given; and though it is not stated which are the most 

 frequent, all valleys are described as more or less distinctly valleys 

 of erosion. 



From the part treating of low plains, we extract a passage refer- 

 ing to the Steppes of the south-east of Europe, which will warrant 

 the wish that we had more instances of such vivid description in 

 the volume: — 



" In these Steppes the seasons are very strongly marked. In the spring and early 

 summer the land is carpeted by flo-wers. In the summer it becomes parched, after 

 yielding as food or hay a fair supply of mixed grasses, which may be stored for 

 winter use ; bat in the latter part of summer and autumn it is perfectly bare and 

 burnt up. In winter, which begins in October, the whole area becomes covered with 

 snow, and this remains until spring. There are no trees on those great plains, and no 

 enclosures of any kind ; but at intervals the surface is broken by hollows scooped 

 out of the plain, to a depth varying generally from fifty to one hundred feet : and in 

 must of these are villages and some cultivation, especially on the borders of the plain, 

 and in the vicinity of the coast, or of the great rivers. There are, however, no roads, 

 and indeed there is no material for making them. 



