in the Neighbourhood of Edinburgh. 241 



NW. by W. SE. by E. 



— < Grace- 



Roman 



t mount Mount - 



System. ^-J^v 



• 



I 



Fault. Fault. Faiilt. 



To the west of the line of fracture described, strata of sand- 

 stone are thrown into a vertical position, or nearly so, as was 

 shewn in an old quarry adjoining the village of Burdiehouse, 

 which is now filled up. But similar phenomena may be still ob- 

 served within the park of Gracemount, where the same continu- 

 ous strata, consisting of a pale, yellow-coloured micaceous sand- 

 stone, with a direction from S. 10° E. to N. 10° W., are inclined 

 to the south-east, at so great an angle as 80°. These strata ap- 

 pear to have been the tilted beds which had been thrown on 

 edge during one of the convulsive movements connected with 

 the evolution of the trap of the Pentlands, to which range of hills 

 they are contiguous. 



The limestone of Burdiehouse, however, which is situated to 

 the east of these nearly vertical beds, dips no more than from 

 23° to 35° to the south-east, and shews in other circumstances 

 that it was thrown up by an anticlinal force distinct from that by 

 which the strata to the west of it appear to have been tilted, 

 though originating doubtless from the same general cause. 



The nearly vertical sandstone of Gracemount forms a good 

 freestone. It is of a light yellowish colour, and it contains mica 

 as an ingredient. In the less inclined sandstone of Craigmillar, 

 which is apparently a continuation of the Gracemount bed, and 

 which shews many variations of colour, as light yellowish, grey, 

 or even pale red, some of the strata enclose very small attrited 

 portions of quartz, as well as of a substance, which, from its mixed 

 siliceous and argillaceous character, and from its grey, or bluish- 

 grey colour, may be considered as the detritus of older grauwacke 



VOL. XIII. part i. h h 



