132 Reviews — Desert Conditions Past and Present. 



X.— Desert Conditions Past and Present. 

 Das Gesktz der Wustenbildung in Gegenwart und Vorzeit. By 

 Johannes Walther. pp. xv + 342, with 147 illustrations in 

 the text. Leipzig: Quelle & Meyer, 1912, Price 12 marks. 



AMONG those who have studied and described the characters of 

 desert regions and have thrown light upon the conditions which 

 prescribe their formation, Professor Walther occupies a prominent 

 position. The volume which he issued in 1900 on the subject 

 immediately attracted wide attention and some little controversv. 

 With the publication of that work, however, his interest in the 

 subject in no way waned, neither was his energy exhausted, and 

 whenever time and opportunity atForded he seems to have found his 

 way to Egypt and to have continued his observations and researches. 

 The outcome is this, the second, edition, which represents the fruits of 

 an almost continuous study of the subject for a quarter of a century. 

 Written in an admirably easy style and amply illustrated with repro- 

 ductions of excellent photographs, the book cannot fail to prove of 

 extreme fascination and absorbing interest, not only to students of the 

 subject, but to any reader with sufficient knowledge of the language 

 to be able to read the book without difficulty. 



The book is divided into four main sections. In the first is given 

 a description of the desert regions as they exist to-day, and the efiect 

 produced by extreme heat and rapid evaporation is vividly brought 

 home to the reader. In the next the author describes the erosion 

 produced by the action of wind and sand, and by the torrential cloud- 

 bursts which occasionally occur ; the effect of weathering is very 

 clearly visible in the case of the statues remaining in some of the 

 ruined temples in Egypt. In the third section the author considers 

 the formation and nature of the deposits which have resulted from 

 the actions described in the previous section ; and in the fourth and 

 last he discusses the deserts of past ages, which have resulted in the 

 immense beds of rock-salt and gypsum, containing the relics of 

 a marine fauna, poor in species, but rich in individuals, found in 

 various parts of the world. The value of the book is increased 

 by the list of references and the complete index given at the end. 



XI. The Dover Coal-fikld. — In the Geological Magazine for 

 April, 1890 (p. 192), we announced, on the authority of Professor 

 W. Boyd Dawkins, the discovery of coal in the boring at the foot of 

 Shakespeare's Cliff. We read in the Daily Mail of February 4, 1913, 

 that "coal from Snowdown Colliery, between Dover and Canterbuiy, 

 was yesterday put on the local market by coal-dealers at prices 

 slightly below those of imported coal. This is the first Kentish coal 

 to be publicly marketed ". The colliery is close to the Fredville 

 boring and about 7 miles south-east of Canterbury. 



It is interesting to receive at the same time an article on "The 

 South-Eastern Coal-field, the Associated Kocks, and the Buried 

 Plateau", by Professor Dawkins (Trans. Inst. Mining Eng., xliv, 

 pt. ii, p. 350, 1913). He gives a plate, with three maps and two 

 longitudinal sections, to show (1) the area of the South-Eastern 



