118 MR. T. I EIGHT IX OX THE LOWER [^lay 1 895, 



consists of sands. These are whitish-grey and glauconitic. Below a 

 well-marked line of chert is a bed of fairly compact greensand, then 

 follow looser grey coarse sands (strongly glaucouitic), so far as the 

 slopes allow of observation, to the floor of the pit. Ironstone occurs 

 along lines of infiltration throughout the lower beds, but this is 

 quite a usual phenomenon in sandy and similar soft beds, and is 

 probably of no stratigraphical moment. 



A few score yards farther on, just through the escarpment, a gate 

 on the west leads to a noteworthy section in a small plantation. 

 The whole series of beds from the Fuller's Earth to the beds of Local 

 Group 4 are here shown, thrown down by a fault, the angle of 

 the upper beds approaching the perpendicular. In a small pit a 

 search has apparently been made for the blue rock below the Fuller's 

 Earth, since it is of considerable commercial importance as road- 

 metal, on account of the binding qualities of the lime. The massive 

 cherts and associated beds, however, alone occur ; and, as it is some 

 time since the pit was abandoned, the section is not so clean as 

 might be wished, but on careful examination measurements can be 

 obtained without much difficulty. 



The calcareous series with the blue rock, exposed only 1300 feet 

 farther north (a little west), as the crow flies, remains a mystery 

 which I cannot explain. The beds here are the same as those 

 exposed in the lane by Rabbitsheath Cottages, and unless the fault 

 at the latter place has a much greater throw than appears, there is 

 not room for the cherts to pass below the calcareous beds ; again, 

 the presence of Fuller's Earth at the top of the chert series in the 

 Tilburstow Hill Fault pit and at the top of the calcareous series in 

 the Plantation pit suggests a lithological change from south to 

 north, although there is little room for that either. Yet some such 

 change probably takes place ; a 12-inch bed of limestone has been 

 already referred to as overlying the cherts at this horizon (p. 116). 



The following is the section in the Fault pit. Dip iN T ., top of 

 the section about 500 O.D. : — 



'Sandy Fuller's Earth, etc 2 feet. 



Massive chert and interbedded layers of cberty sand- 

 stone 20 feet. 



Hard stone-beds of massive greensand, perhaps slightly 



cherty, particularly in the upper portion 15 feet. 



Hard beds, rather uncertain ; no blue rock or other 



calcareous beds 10 feet. 



Cherty rubble sandstone-beds, as on Tilburstow Hill 



Common, etc 10 feet. 



Coarse sand, strongly glauconitic 20 feet. 



Pebble sandy-bed, false-bedded, finely stratified ; dark 



sandy matrix ; usual Bargate pebbles 2 feet. 



Coarse many-coloured sands ; becoming red-brown, 

 clayey, and finer low down ; thickness not clear, as 

 the bedding rapidly becomes normal, or uncertain 

 from false-bedding ; but at least 40 feet seen. 



hi a 



Hi 2 



3 



