Vol. 63.] SILURIAN INLIER IN THE EASTERN MENDIPS. 221 



the specimen from Beacon Hill described by Dr. Teall ! was probably 

 obtained. Much trap-debris occurs in the northern part of this field. 

 East of the ' Waggon & Horses ' Inn, trap-debris has been found at 

 a number of points, as indicated in the map (fig. 1, p. 220). These 

 indications tend to show that the trap-band here is about 200 yards 

 wide. The westernmost point at which trap is now seen definitely 

 in situ is at a clump of trees about 150 yards west of Sunnyhill 

 Quarry, but the exposure is poor. Sunnyhill Quarry, so interesting 

 from its fine section of tuffs, is principally opened in fresh andesite, 

 which closely resembles that of Moon's Hill as well in its tex- 

 ture and composition as in its generally shattered and slickensided 

 character. Flow-structure is sometimes clearly seen. At one spot 

 the lower part of the trap has caught up and enclosed a mass of 

 red shaly material. The cutting-back of the northern side of the 

 approach to the quarry has exposed a mass of tuff and shaly 

 material about 25 feet thick, underlain by some 25 feet of trap. 

 This is described on p. 223. 



The Moon's-Hill mass. — A short distance north-east of 

 Sunnyhill Quarry is the big quarry of Moon's Hill, where stone, 

 which is much used locally for road-metal, has been quarried for 

 many years. Moon's-Hill Quarry — by far the largest in the igneous 

 series of the district — is opened in a singularly-uniform mass of 

 compact andesite, dark purple or sometimes dark green in colour, 

 with prominent dark-green augites. It is never markedly amygdal- 

 oidal, and is much shattered and faulted, showing in places strings 

 and patches -of epidote. In the smaller and more northern quarry, 

 and in the little excavation between the two quarries, the rock is 

 more weathered than in the main quarry, but the same general 

 rock-type occurs throughout. It is very difficult to obtain any 

 clear idea, either as to the thickness of the Moon's-Hill trap, or as 

 to its dip. The most prominent divisional planes traversing it dip 

 in a south-south-westerly direction at an angle of about 40°, which 

 would give a strike nearly at right angles to the igneous band as a 

 whole. Mr. Dixon, however, detected a second series of divisional 

 planes, dipping north-north-westward at a very high angle, and thus 

 giving a strike coinciding with that of the igneous series as a 

 whole, and with that of the lines of flow -structure which are some- 

 times visible on the weathered surface. If these divisional planes 

 really indicate the dip and strike of the trap, and if the high dip is 

 maintained and there is no repetition by faulting, the thickness of 

 the trap must be at least 900 feet. It is not, in any case, probable 

 that the trap is less than 400 feet thick at Moon's Hill. 



Fragments of trap were obtained along the hedge-bank to the 

 south-east of Moon's-Hill Quarry ; but from this point until Tadhill 

 Farm 2 is approached (a distance of about half a mile) no clear 



1 ' Summary of Progress of the Geological Survey for 1898' (1899) p. 111. 



2 In the 6-inch Ordnance-map two Tadhill Farms are shown — one south of 

 the Frome Road and west of Tadhill House, the other north of the Frome 

 Road and east of Tadhill House. When ' Tadhill Farm ' is referred to in the 

 present paper the former of these is meant. 



