91 



C^e 6eologD of t|e lailfoan §^me from 

 Cljiselbon to CoUingbounie. 



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

 IBead at the Marlborough Meeting of the Society, July 2Qth, 1894.] 



fN 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 Geology of the Berks 

 and Hants Extension Railway," published ia 1865. 



AVlien that paper was written the line from S^vindon to Andover 

 did not of course exist. 



I propose now to describe the geology of the cuttings from 

 Chiseldon to CoUingbom-ne. 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 liae 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 theu- purpose. 



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

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



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

 VOL. xxvm. — NO. Lxxxm. h 



