A RAMBLE THROUGH CATERHAM VALLEY. 139 



after it the various beds we walked over in coming 

 from Caterham, though of course in the reverse 

 order to that in which we then observed them. 



Thus much for the physical aspects of the Geology 

 of this district. A few further particulars of a more 

 palseontological character may be added. 



The fossils of the London Clay are very numerous 

 in some localities, but not in the one now under 

 survey. Marine creatures, such as Nautilus, crab, 

 fishes, are found, along with estuarine forms, Voluta, 

 Fusus, etc., and sufficiently indicate the nature of 

 the deposit. 



The Woolwich and Reading beds consist of 

 mottled clays and sand, and in them are found 

 fossils of both salt-water and fresh-water species. 

 The Thanet beds at Croydon do not appear to be 

 fossiliferous. 



Passing on now to the Secondaries, we are at 

 once confronted with the enormous chalk deposits 

 which stretch for a distance of seven miles from 

 Croydon to Caterham, and attaining in some places 

 a thickness of five hundred feet or more. In the 

 quarries and railway cuttings numerous fossils may 

 be obtained with very little labour. Various kinds 

 of sea-urchins (Micrasters, etc.) and ammonites 

 abound. Foraminifera for the microscope may also 

 be got in profusion. These organic remains con- 

 clusively show that the hundreds of feet of chalk 

 were slowly deposited by the dropping of the shells 

 of dead animals upon the bed of a vast deep sea, 

 just as is now going on in the Atlantic, from the 

 depths of which the Challenger naturalists have 



