Revieics — Penning and Broicne's Geology of Cambridge. 565 



" Terrible and striking, then, as are the phenomena connected with 

 volcanic action, such sudden and violent manifestations of the sub- 

 terranean energy must not be regai'ded as the only, or indeed the 

 chief, effects which they produce. The intei-nal forces continually 

 at work within the earth's crust perform a series of most important 

 functions in connexion with the economy of the globe, and were the 

 action of these forces to die out, our planet would soon cease to be 

 fit for the habitation of living beings " (p. 302). 



It would be impossible to give an adequate notice of Prof. Judd's 

 admirable work in our limited space. Fortunately, however, the 

 book is so planned, both for size and price, as to bi'ing it within the 

 reach of every student of Geology ; and every student should possess 

 a copy. 



In conclusion, our readers may be reminded that some of the 

 earliest and most valuable of Prof. Judd's studies of Volcanos in 

 Italy and Hungary appeared as Original Contributions to the 

 pages of this Magazine for 1875, pp. 1, 56, 145, 206, 245, 298, 348, 

 388, 482, and 1876, pp. 5, 53, 200, 337, 487, 523, 529. 



II. — The Geology of the Neighbourhood of Cambridge. By 

 W. H. Penning and A. J. Jukes-Browne. Memoirs of the 

 Geological Survey of England and Wales. 8vo. pp. 184. 

 (London, 1881.) 



THAT a Memoir of the Geological Survey of the size above 

 indicated, and accompanied by twenty-three woodcuts, three 

 plates of fossils, two coloured maps, and two plates of sections, 

 should be published at 4s. 6c?., is such a marked improvement in the 

 price of Survey publications, that we feel bound to call attention at 

 once to this great reduction in cost, which we hope may be main- 

 tained in the future. 



The Memoir now before us is an explanation of Quarter-sheet 51 

 S.W., with part of 51 N.W., of the Geological Survey Map, and 

 although it will not compare in point of scope or popular interest 

 with Professor Bonney's Geology of Cambridgeshire, it furnishes a 

 detailed account of the geological facts connected with a portion of 

 the county which cannot fail to be of scientific as well as practical 

 value. The formations described include the Oxford Clay, Kimmeridge 

 Clay, Lower Greensand, Gault, Chalk, Glacial and Post-Glacial Drift. 

 In their account of the Chalk the authors have added much to what 

 was previously known, and their labours lead them to feel confident 

 in the existence of zones in the Chalk, and that these are remarkably 

 constant thi'oughout the whole extent of the escarpment from 

 Dorsetshire to Cambridgeshire. In this respect they corroborate 

 and supplement the work of Dr. Barrois. Further, in the larger 

 divisions under which the zones may be grouped, they apply the 

 general classification proposed in 1833 by Samuel Woodward for 

 the Chalk of Norfolk, thus making Upper, Middle (or Medial), and 

 Lower divisions. 



A general account of the palseontology of the different sub- 



