Vol. 55.] STRFCTTTRE OP THE S0T7THERN MALTERNS. 



141 



cottage-orchard. The dip behind the cottage is to the west of south 

 at 7o°, while immediately to the west the dip is west-south-westerly 

 at 33°. It may be noted that the strike of the beds of the southern 

 portion of the strip is almost straight across the length of the latter : 

 while close to the quartzite (M 173 a) the sandstone dips at 20° west- 

 north-westward, and strikes obliquely across the strip. In all proba- 

 bility a transverse fault cuts off the southern portion of the strip. 



The south-western corner of Midsummer Hill is formed by a 

 quadrangular patch of Hollybush Sandstone, invaded by a number of 

 small intrusive masses of andesitic basalt. It stands out as a well- 

 defined small hill, on the northern bank of the stream running 

 down the Hollybush Pass. It is bounded on aU sides by faults ; of 

 these (four in number) that on the west, which separates it from a 



Fig. 10. — Section across Midsummer and Hollybush Hills. 



[Scale 



i^i^= Faults. 

 ^= Trias. 



^=May Hill Sandstone. 

 /=Grey Shales (Cambrian). 

 e= Igneous rocks in Black Shales, 



4^ inches = 1 mile.] 



(^= Black Shales (Cambrian). 

 c = Hollybush Sandstone. 

 6=: Hollybush Quartzite. 

 «=Arcb£ean. 



faulted block of May Hill Sandstone, is difficult to trace. The dip 

 of the Hollybush Sandstone in this varies from 33° west-south- 

 westward to 40° west-north-westward, and thus approaches closely 

 that noted on the other side of the Hollybush Pass. 



That intrusive mass of which the relations are seen most clearly, 

 is well exposed in a small quarry on the road from Hollybush to 

 Upper House Farm. The dyke is there observed to dip eastward, 

 at an angle of 45° (see fig. 9). The intrusive character of this 

 dyke was recognized by Phillips.^ 



Four of the faults to which reference has been made enclose 

 another quadrangular area (see map, PI. XIII), the southern part 

 of which at least, and, as I believe, the whole, is occupied by Black 

 Shales, here, for the most part, baked grey by an associated series 

 of andesitic basalts. The dip of these shales at the south-western 

 corner of the patch is 25° to west by south; while near the 

 south-eastern corner it is about west 37° north at 56°. One of 

 the intrusive masses forms a well-marked, rounded boss, but the 

 majority appear to be small sills. 



1 Mem. aeol. Surv. vol. ii (1848) pt. i, p. 53. 



