84 Reviews — P. Lake ty R. H. Rastall — Text-Book of Geology. 



the glacial deposits about the western end of Lake Ontario, though 

 not so recent as the later Wisconsin accumulations in other localities. 



Before the birth of the falls the ice-sheet had receded beyond the 

 greatest of all the moraines of Ontario, which lie between Lake 

 Ontario and Lake Simcoe and between this lake and Georgian Bay, 

 a distance of more than 120 miles north of Niagara Palls, so that 

 the drainage of Lake Huron then passed down the Trent Yalley. 

 From the terrace north of Lake Nipissing the ice-sheet had receded 

 230 miles or more to the north of Niagara before the birth of the falls. 

 But the Ottawa Valley farther down was still blocked. The Ontario 

 Valley was open to at least near the eastern eud of the lake, so that 

 it permitted the flow from Algonquin Lake clown the Trent Valley, 

 although the ice was not removed from the St. Lawrence till some 

 time after the birth of the falls. This was the last ice-sheet, and we 

 only know that it disappeared so long ago that there was time 

 for the excavation of the inner gorge of Niagara River, extending 

 from Lake Ontario to a point inside the canyon of Niagara, since 

 reflooded and drowned 180 feet by the subsequent north-eastward 

 tilting of the region. 



ZRZE^IIE-WS. 



I. — A Text-Book of Geology. By Philip Lake, M.A., P.G.S., and 

 R. H. Rastall, M.A., P.G.S. 8vo ; pp. xvi, 4 94, with 32 plates 

 and 134 text-illustrations. London : Edward Arnold, 1910. 

 Price 16s. net. 



THIS volume, issued as one of " Arnold's Geological Series" under 

 the general editorship of Dr. Marr, is of larger dimensions than 

 the series in course of publication on Economic Geology. As a text- 

 book it will occupy an appropriate position between the Geology for 

 Beginners of Professor Watts and the two-volume textbook of 

 Sir Archibald Geikie. In the first part Mr. Rastall gives a clear and 

 concise account of the principles of the science as illustrated by agents 

 now at work ; he describes rock-structures and earth-movements, and 

 gives special petrological descriptions of the igneous rocks, of meta- 

 morphism, ore deposits, and mineral veins, occupying in all 279 pages. 

 In the remaining portion, also admirably executed, Mr. Lake deals 

 with the principles of stratigraphy, and with the fauna and flora of 

 the great geological systems. 



The book is well printed, admirably illustrated, and it has a good 

 index ; above all, it is written by two experienced workers and 

 teachers, who have brought before us the latest results of geological 

 research. Pew references, however, are given to authorities. 



The student will welcome the exposition of rock-structures, of folds, 

 and the formation of overthrusts, the treatment of earth-sculpture and 

 of the agents of denudation, attention being called to the dominant 

 action of particular agents of weathering, transport, and corrosion 

 under different climatic conditions and in different latitudes. 



The development of rivers is explained in diagrammatic form, but 

 the student has to bear in mind that the actual river-courses are liable 



