91 



Oe 6cologn of % IJwlfosg Jiite from 

 CImdbou to CoIUngbttrne. 



By F. J. Bennett, F.G.S., H.M. Geological Survey * 

 [Read at the Marlborough Meeting of the Society, July 20th, 1894] 



N responding to a request for a paper on the geology round 

 Marlborough it occurred to me that the best thing to do 

 would be, in a measure, to supplement the admirable paper by 

 Mr. Codrington in the Magazine, on " The Greology of the Berks 

 and Hants Extension Railway," published in 1865. 



"Wlien that paper was written the line from Swindon to Andover 

 did not of course exist. 



I propose now to describe the geology of the cuttings from 

 Chiseldon to Collingbourne. These cuttings are so familiar to 

 many of you that I hope you may be easily able to follow the 

 diagram I have prepared to illustrate the various strata shown. 



In addition to a diagrammatical section of these cuttings there 

 is attached to them a plan or map of the geology of the country 

 to the east of the line. This has been given to show how a cutting 

 may help in the making of a geological map, and may also help to 

 explain a process that very often puzzles people. 



The cuttings, then, show in section, the geology of the country 

 through which the line passes, and the map shows in plan, how the 

 beds seen in the cuttings crop out and appear at the surface of the 

 ground to the east of the cutting. 



Diagrams are not as clear to most persons as their makers 

 generally suppose them to be, and so often fail of their purpose. 



The clearest way, of course, would be to show all this by models, 

 At our Geological Museum in Jermyn Street, London, may be seen 



* With the permission of the Director General of H.M. Geological Survey. 

 VOL. XXVIII. NO. LXXXI1I. H 



