Chiseldon to CoUingbounie. 97 



comes in due course. But in villages on the upper greensand the 

 carelessness that is usually exhibited is most amazing. 



The sanitation of village schools, where the greater part of the 

 juvenile population of the village is centred for so many hours 

 during the day is a most important matter ; here, again, no cesspits 

 should be allowed but all refuse should be bestowed daily in the 

 soil. "Wliere this method is not adopted epidemics are likely to 

 occur. 



Thus, narrow as is the outcrop of the upper greensand, yet, from 

 the number of villages situated upon it, it is a most important 

 formation. Agriculturally also it is important as forming the best 

 land. 



The Lower Chalk. 

 This is the division of the chalk next above the upper greensand. 

 The base of the lower chalk is marly, and is known as the chalk 

 marl. The chloritic marl referred to before is the base of the chalk 

 marl, and shows strong current action with consequent erosion, and 

 contains fossils derived from the upper beds of the upper greensand 

 — the Pccten aspcr zone. 



The chalk marl is a thick-bedded marly chalk, well shoAvn at 

 Chiseldon Railway Station. A little further south a change sets in 

 and we find some thinner, harder, gritty, siliceous beds. These 

 seem to point to the fact that the sea of the lower chalk was 

 still within the influence of a current bringing fine sand. The 

 depth of this sea has been estimated at from three hundred to fovir 

 hundi-ed fathoms. The glauconite so abundant in the upper 

 greensand lessens in the chalk marl till it disapj)ears in the upper 

 beds of the lower chalk. 



The lower chalk near the escarpment occupies a considerable area, 

 so that it is there an important division. 



The cuttings in this di\asion, owing to its much greater thickness 

 — the dip not varpng very much — extend for some thi-ee miles along 

 the line, a great contrast to the naiTOW outcrop of the gault and 

 the upper greensand. A reference to the diagram where this 

 division of the chalk is marked 4c wiU show this faii'ly welL 



