8 Geology. 



As regards the western portion of the area, very little Chalk is 

 exposed. In the extreme south-west, at Keston, just after 

 emerging from Hoi wood Park the Chalk again appears, and at once 

 gives the characteristic features to the scenery. About a quarter 

 of a mile from the Park on the Westerham road, there is an 

 interesting chalk-pit, known as Leaves Green Pit. 



Proceeding from Keston Church toward Farnborough, small 

 exposures of chalk are seen in the roadsides. 



Before describing the Chalk forming the southern limit it will be 

 worth while to draw attention to what has been done in zoning 

 the Chalk during the past 25 years. Before this time the Chalk of 

 England was described as Lower, Middle and Upper Chalk (names 

 still useful in a broad sense). About 1870 Dr. Charles Barrois, a 

 celebrated French geologist, paid a short visit to this country for 

 the express purpose of correlating the English Chalk with that of 

 France, as regards the fauna ; and the English Chalk was zoned by 

 him according to the life-bands, as marked by dominant fossils. 

 Now the Chalk has been zoned from bottom to top. This work has 

 been done in an admirable manner along the coast by Dr. Rowe, 

 of Margate, and Mr. C. D. Sherborne, who have inspired others to 

 take up the work in inland districts. 



In former days the chalk exposed in our district would have been 

 regarded as the uppermost part of the Upper Chalk, whereas we 

 now know that it forms the lowest division of the Upper Chalk, 

 which is here characterised by the typical sea-urchin MICE ASTER 

 COR-ANGUINUM and other echinoderms, such as ECHINOCORYS 

 SCUTATUS and CONTJLUS ALBOGALERUS (formerly known as ANAN- 

 CHYTES OVATUS and GALERITES ALBOGALERUS) . Beautiful forms of 

 the CIDARID^E, CYPHOSOMA, and other Echinoids characterise this 

 Chalk which is known as belonging to the MICRASTER COR-ANGUINUM 

 zone. It must be about 200 feet thick here. 



This zone is followed upward on the Kentish and Sussex coasts 

 by zones marked by the presence of two interesting forms of 

 Crinoids (a group or division of the Echinodermata), one 

 (the UINTACRINUS) being very small, and which escaped atten- 

 tion in this country till brought to light by Dr. Rowe. This 

 fossil, unfortunately, is found, as in the case of the Cidaridae, in 

 the form of detached plates and arm-ossicles, so small that they 

 are very likely to be overlooked by the collector. This band is of 

 no great thickness, and is succeeded upward by Chalk containing 

 another Crinoid, the Marsupite, whose large plates cannot fail to 

 attract the eye. 



This zone is followed by others, but, as the Woolwich district 

 does not contain these upper zones, there is no necessity to say 

 more of them. Till last April the writer (who has zoned the 

 extensive chalk-pits in the Rochester, Gravesend, Dartford, Charl- 



