^Ol* 55-J STRUCTURE OF THE SOUTHERN MALVERNS. 163 



of the cottage immediately west of Powlet Parm, a porphyritic 

 basalt (M 356) is exposed in the hedge-bank ; and Powlet Farm 

 itself is situated on similar basalt (M. 451). A considerable hump of 

 an oval shape (K 224: & 198) is situated south of M 104, The 

 rock itself is not exposed here, but the debris abounding on the 

 surface of the ploughed field which covers it indicate the presence 

 of much basalt. 



Diabase (jSL 447) ^ is exposed on the road between Powlet Parm 

 and the cowshed south-east of this, and the cottage immediately west 

 of Powlet Parm is situated on another patch of diabase (M 372), well 

 shown in the road. 



The shales with which these igneous rocks are associated are very 

 imperfectly exposed ; the area north of the igneous bosses near 

 Martins is covered by a thick deposit of Drift, and excavation in the 

 lower ground failed to reach the rock. 



Much indurated shale of a light colour, such as is found in con- 

 nexion with the igneous rocks in both the Black and Grey Shales, 

 occurs with the basalt of M 224 & 198, but no unaltered Elack 

 or Grey Shale was seen here in sufficient abundance to enable me to 

 determine whether the basalts belong to the Black or to the Grey 

 Shales. In a little hollow, however, immediately west of M 224, 

 generally occupied by a pool. Black Shales are seen dipping west by 

 south at 30°. These appear to be faulted against the Coal Hill 

 igneous band, which is seen immediately to the westward. This 

 suggests that the basalts on the north-east are also in Black Shale. 

 Black Shale occurs associated with the basalt at M 356. 

 A well sunk many years ago, to a depth of 84 feet in the orchard of 

 the cottage west of Powlet Parm, and immediately south of the dia- 

 base M 372, showed, as I am informed by the cottager, nothing but 

 Black Shale and 'yellow stuff' (perhaps weathered basalt or diabase); 

 and in a trench cut across the orchard a short time ago I observed 

 a great quantity of disturbed Black-Shale debris, almost certainly 

 thrown out from this well. An excavation (M 194) made many 

 years ago south-west of the well, apparently in search of coal, shows 

 abundant debris of Black Shale, and similar fragments seen in the 

 hedgerow seem to connect this patch with that of the well. 



These occurrences indicate the existence of one or more faulted 

 blocks of Black Shale in the district. Possibly, all the igneous masses 

 enumerated above belong to two or three such patches, and as such 

 I have provisionally mapped them, though it must be clearly under- 

 stood that this point is by no means certain. 



The northern slope of the ridge between Powlet Parm and Martins 

 is largely formed by the Grey Shales. These are exposed in the 

 main road north of Powlet Parm, where the beds dip irregularly in 

 a northerly direction at a low angle. West of this point, and 

 directly along the line of strike of the Coal Hill igneous band, is a 

 quarry in a mass of diabase (M 106) crossing the road. Debris of 

 the same rock associated with indurated shale may be traced up the 



1 [Omitted from the map, PI. XIII.] 



m2 



