S06 Mr. Maclauchlan's Notes to accompany a Geological Map, S^c. 



considered as continued into this great fault from the Leech Pool to beyond 

 Denbigh Lodge, another description of continuation of it, is in the line or axis 

 which runs into the coal-field through the successive points of acute flexure 

 made by the different beds or '' delves " of coal. 



This flexure or irregular basin shape seems here moulded by the two un- 

 conformable dips of the old red, which the fault at Ailberton divides ; but 

 they seem to bend from one position to the other less abruptly, and with less 

 dislocation of the strata, than near Ailberton. 



It is suspected, however, that at the bend of the upper coal beds at White- 

 croft, there is some little dislocation ; and very possibly near Lydney, the Cole- 

 ford High Delf does not bend so completely without dislocation, as it is repre- 

 sented to do in the map. 



In that part of the line, where the fault runs nearly parallel to the strata 

 on both sides, it has not been found possible to distinguish clearly one 

 formation from the other, or consequently the exact line of dislocation. The 

 characters of the millstone grit and old red are likewise not well defined. 



A remarkably hard, fine-grained, purplish rock occurs, in white clay, at Old 

 Croft, also at a spot further on in the Forest, and a similar rock appears near 

 Bream. It sometimes contains quartz pebbles, and is possibly a variety of 

 millstone grit. It has a slight mixture sometimes of calcareous matter ; and 

 limestone itself is here occasionally subordinate to the grit*. Its position, 

 however, partakes somewhat of the obscurity, already mentioned, respect- 

 ing this line of fault, from the Leech Pool near Lydney, to Old Croft in the 

 Forest. 



* At Clearwell Meend, near Coleford, the limestone is worked in two places in the millstone 

 grit ; and small pieces have been dug out at Old Croft bearing the red sandy appearance of that 

 at Clearwell Meend. 



