32 Notices of Memoirs — Geological Diagrams and Models. 



Ill, — Geological Diagrams and Models. 



Table of British Sedimentary and Fossiliferous Strata. By 

 Henry William Bristow, T.E.S., F.G.S., Director of the 

 Geological Survey of England and Wales. With a Description 

 of Life Groups and Distribution, by K. Etheridge, F.E.S. 

 (Stanford.) 



Geological Models of England and Wales. By William Topley, 

 F.G.S., Geological Survey of England and Wales ; and J. B. 

 Jordan, Mining Eecord Office. (Stanford.) 



WHILE the progress of geology is revealed in one way by the 

 numerous manuals and text-books, it is shown in another 

 way by the charts, tables, maps and models, which are from time to 

 time constructed and published, in accordance with the advancement 

 of the science. Appeals made to the eye are always appreciated by 

 the student, and they are indeed essential as a method of instruction. 

 A glance at a geological map or section will explain more than 

 many pages of print ; but properly to understand these, a good table 

 of strata is necessary. Of course our small geological maps of the 

 British Islands give tables of all the stratified rocks, showing their 

 order of succession, but these cannot furnish much detail, and when 

 we take maps on a larger scale, of course we cannot have represen- 

 tations in them of the whole series of strata. A table showing, not 

 only the minor divisions of the British sedimentary and fossiliferous 

 strata, but also the local divisions which have been made, as in the 

 Inferior Oolite of Gloucester, the Midland counties, and Yorkshire ; 

 or in the Silurian rocks of Wales and the Lake district ; is an 

 essential diagram in the hands of all geologists. Such a table has 

 just been prepared by Mr. Bristow, which is published by Stanford. 

 In it are embodied all the latest modifications in our classification of 

 strata, and it is as a table of classification that it will be most appre- 

 ciated, because it does not furnish the notes on the economic uses of 

 the rocks or their characteristic fossils, which are to be met with in 

 other geological charts. It contains, however, a very useful sum- 

 mary of the life groups by Mr. Etheridge, arranged zoologically, 

 and then giving their geological distribution. This table will be 

 found of great service to the student while reading a geological 

 manual ; and in illustrating the succession of our rocks as they are 

 depicted on our geological maps it will be found of great aid. 



A geological map is, however, rarely understood, save by the 

 geologist; for among those who are not adepts much ambiguity 

 prevails as to the reason of the irregular shapes of the many colours 

 on our maps. The relation between the form of the ground and its 

 geological structure is one of the great doctrines of geology, and a 

 knowledge of this adds greatly to the interest and understanding of 

 a map. The small models hmg ago published by Mr. Sopwith were 

 admirable as methods of instruction ; but now we are not satisfied 

 with these — a grander work must be accomplished — the whole of 

 England shall be modelled, we are told, by Mr. Topley and Mr. 

 Jordan. This undertaking is to comprise about sixteen blocks, 



