474 Reviews — The Geology of the London Basin. 



Trigonocarimm, and species of Sigillaria. Several species of 

 Neuropteris, most of the Odontopteris, and several of Aletliopteris, are 

 found only in connexion vnth this bed. A. loncMtica is said to be 

 an unfailing indication of this horizon. Above this bed the Lyco- 

 podiaceous plants diminish in frequency, and the ferns are more 

 important guides in determining the equivalency. Twelve or more 

 horizons are distinguished by M. Lesquereux in the different basins. 

 The theory is not affected by the error in stratigraphy just referred 

 to ; but it is not adopted by the best American palseophytologists. 



III. — The GrEOLOGT OF THE LONBON BaSIN. 



Memoirs of the Geological Survey of England and Wales, 

 Yol. IV. — The Geology of the London Basin, Part I. — The 

 Chalk and Eocene Beds of the Southern and Western 

 Tracts. By William Whitaker, B.A,, London. (Parts by 

 H. W. Bristow, E.E.S.,^ and T. M'K. Hughes, M.A.) . 8vo. 

 pp. 619. (London, 1872.) 



fTlHE geology of the country around London has not been the 

 JL subject of many elaborate memoirs ; indeed, we may say that 

 hitherto the only important works written on this subject were Mr. 

 Prestwich's "Water-bearing Strata," his lectures delivered at Clap- 

 ham on the " Ground beneath us," and a Memoir by Mr, Whitaker 

 on the Geology of parts of Middlesex, Hertfordshire, etc., descriptive 

 of the country embraced by Sheet 7 of the Geological Survey Map of 

 England. We do not mean to hint that the geology has been 

 neglected ; such an idea is sufficiently refuted by reference to the 

 volume before us : for Mr. Whitaker has collected and printed the 

 titles of papers referring to the geology of the country lie describes, 

 numbering no less than 600. Most of these, however, refer only 

 to portions of the country, and not the least arduous task for 

 Mr. Whitaker must have been the preparation of this list, and the 

 gleaning from the papers all facts relating to the subject he had 

 in hand, for now-a-days, in writing even a short paper, the most 

 difficult part is often to ascertain what observers have previously 

 written upon the subject, so as to give due credit to them. 



Mr. Whitaker, who is now, we understand, the senior field geologist 

 on the Geological Survey of England, has personally surveyed a very 

 large portion of the country described. It includes the whole of the 

 counties of Hertford and Middlesex, and parts of Bedfordshire, 

 Buckinghamshire, Essex, Hampshire, Kent, Oxfordshire, Surrey and 

 Wiltshire. 



The formations exposed in this area are the Bagshot Beds, London 

 Clay, Lower London Tertiaries and Chalk. Their general nature is 

 first noticed, and then their range, lithological character, and sections 

 are described in detail. One chapter is devoted to the sands of 

 doubtful age on the Chalk, originally classed with the Crag by Mr. 

 Prestwich, and subsequently referred to the Eocene period by Mr. 

 Whitaker and others. The concluding chapters are devoted to Dis- 

 turbances, with a notice of the likelihood of there being an under- 



