GEOLOGICAL NOTES ON ARBOR LOW. 79 



and have the pot-hole weathering, which is not only a charac- 

 teristic of the upper surface of a bed of limestone which has 

 been covered by soil, or exposed to the air, but also of beds 

 in the mass of the rocks, through which small pipes have 

 been made by the action of water. We may safely conclude 

 that the majority of the Arbor Low slabs once formed part 

 of a bed in the limestone, and that they have been taken from 

 some place where the rock formed part of the ground surface. 

 Near Henmoor, about two miles N.W. of Arbor Low, we found 

 a large slab of limestone very similar to that at Arbor 

 Low, apparently lying on the road side. It measured about 

 10 feet 6 inches by 5 feet. The rock projects above the surface 

 of the ground in several places within a distance of a few 

 yards. The beds are horizontal. The slab, which is probably 

 in situ, could without much difficulty be separated and raised 

 from the bed beneath, on which it rests. 



The parent rock at Arbelow is very different in colour, 

 texture, and composition from that of which the slabs are 

 formed. The site for the stone circle was therefore not 

 selected because the rocks were in situ, but for some other 

 reason. 



A short distance south-east of the circle a dark-coloured 

 dolomitized limestone is seen cropping out above the surface 

 of the ground. The walls of the ditch, and also many blocks 

 of stone in the tumulus, are composed of a similar dark 

 dolomitized limestone which is rough to the touch. The rock 

 is evidently in situ, and the ditch has been excavated in it. 



Scattered about the ground and under some of the slabs 

 are what might be taken for chips of flint. They are chert 

 fragments. Such fragments are very common in the surface soil 

 of the limestone district. On the ground we found several 

 blocks of limestone with nodules of chert embedded in them, 

 and in a small quarry, N.E. of the low, the limestone contains 

 similar nodules of chert. 



