Vol. 51.] GREENSAND OF EAST SURREY. 119 



IV. Comparative Table of Sections of the Lower Greensand 

 between Dorking and Blechingley, to show the Relations 

 of the Different Beds along the Lower Greensand Ridge. 



Notes on the Sections (see pp. 120, 121). 



Fig. 1. — Compiled chiefly in Punchbowl Lane; the relative thickness of sands 

 and clayey sands above the bed of chert is not clear. The thickness 

 of the bed of chert is exaggerated in the figure. 



Fig. 2. — Upper third of the section from Bell Street. The demarcation of the 

 clayey sands from the sands above and below is not clear. 



Fig. 3. — Upper half of the section from larger pits on Redhill Common. The 

 junction of the Folkestone Sands and Fuller's Earth is not shown, 

 and its nature cannot be otherwise ascertained. 



Fig. 4. — Upper two-thirds of the section from the Cockley and Park Fuller's 

 Earth Works, and from the lane to Little Cormonger's Farm. The 

 thin beds are slightly exaggerated, and the relative thicknesses of the 

 sands and clayey sands are difficult to ascertain. This section shows 

 the Lower Greensand to be somewhat thicker at Nuffield than east and 

 west of that village. This may be a local phenomenon, or it may be 

 due to an error in the determination of the position of the outcrop of 

 the Atherfield Clay (mapped from surface-indications only) in con- 

 sequence of undiscovered slips of sand ; or again, it may be due to a 

 change in the angle of dip in the lower beds (where the excess is here 

 shown). When not shown in section, the thickness of all these beds 

 has been calculated from outcrop to outcrop at the same dip as seen 

 above or below, as the case may be. East of Nutfield a similar section 

 can be compiled, from the Nutfield Chert-bed downwards. 



Fig. 5. — No evidence above the topmost sandstone ( 1 foot). Upper fourth of the 

 section from the lane east of the Castle, the remainder from surface- 

 indications entirely. ' 



Fig. 6. — Section from Outward Lane. The limestone is thicker here than to 

 the east, and massive cherts now first appear in quantity. Upon this 

 horizon the chert increases, and the sand associated with it decreases 

 in quantity in passing westwards ; these beds cap the Nutfield- 

 Blechingley ridge almost constantly. The coarse sands are not suffi- 

 ciently well shown to display the Pebble-bed here, but it probably 

 occurs, as in the Fault pit at Tilburstow Hill, in a rudimentary 

 condition. Limestone is first seen here on the probable horizon of the 

 Kentish Pag, but it may have come in earlier, where these beds are 

 mapped from surface-indications only. 



V. Conclusions. 



The occurrence of fragments of the chert-beds over the surface of 

 the Weald Clay S.S.E. of Dorking, and the presence of pebbles of chert 

 in the alluvium and in the beds of the streams flowing from the 

 same district (even to beyond the Lower Greensand escarpment, and 

 yet east of the gap formed by the Mole in the Chalk at Dorking), 

 clearly prove that at one time the Chert-beds existed east of where 

 they are now seen in situ. But since the Lower Greensand area to 

 the north of that district consists of sandy beds only, or at most 

 contains only a thin bed of chert in the clayey sands, there must be 

 a lithological change from south to north on this horizon [from less 

 littoral to littoral conditions]. The quantity of Bargate debris in 

 the drifts south and east of Dorking suggests further a thickening 

 of these beds to the south also. In the Godalming-Guildford district 

 Mr. Meyer, the officers of the Geological Survey, aud Dr. Hinde 



