PRE-DP:VONrAN ROCKS OF TttE MENDlPS AND TflE BRISTOL AREA. 287 



was not made till his paper on the ' Silurian Inlier of the Eastern 

 Mendips ' had already beexi published, ' and the main part of the work on 

 this part of the area had been done. With the aid of the grant, however, 

 several trenches were dug, and a good deal of additional information was 

 obtained both from them and from new exposures made in connection 

 with quarrying operations. Unfortunately, however, it did not prove 

 possible to ascertain the relations of the coarse ashy conglomerate, the 

 most remarkable deposit of the district, to the other rocks. The 

 additional information obtained from various sources since the publication 

 of the paper already referred to is as follows : — - 



1. Beacon Farm Neiyhhourhood. — Three trenches were dug here ; the 

 first was one-third of a mile N.E. of Beacon Farm, close to the north- 

 eastern border of a plantation. The material here is coarse ashy 

 conglomerate, exactly like that at the Butts on Beacon Hill. Precisely 

 similar material was reached at a depth of 3 feet in a trench dug close to 

 the Roman road and about 300 yards N.E. of the previous trench. 

 These trenches prove that the eastward extension of the coarse ashy 

 conglomerate is much as was previously mapped ^ on evidence derived 

 from material thrown out by moles and rabbits. A third trench at a 

 spot nearly a third of a mile N.W. of Lodge Farm was taken down 

 7^- feet through loose material full of pieces of trap without anything 

 in situ being met with. It is, however, practically certain that the 

 material here is the trap (andesite). 



2. Sunnyhill and Moons Hill. — The following section, essentially the 

 same as that in the Sunnyhill quarry, was exposed near the wind pump 

 just S.W. of the quarry : — 



Ft. In. 

 4. Compact andesite to top of section ..... 



3. Highly vesicular andesite 3 



2. Very tine red ashy clay 13 



1. Fairly coarse tuff . . . . .. , . .120 



Thickness of ashy series seen . .13 3 



The vesicular andesite has vesicles an inch long : the big ones are 

 empty, the little ones filled with chlorite ; the rock is a noteworthy one, 

 as on the whole a vesicular structure is very little met with in the inlier. 

 There are indications of banding in the compact andesite, the ban dine 

 being parallel to the base of the mass. The line of junction of the 

 andesite and ashy clay is slightly undiilating, and is clearly one of 

 deposition, not of faulting or intrusion. 



At the time of publication of the previous paper no remains of 

 trilobites had been found in the fine tuff of Sunnyhill, but a single tail of 

 Fhacops has since been obtained. 



Hitherto nothing but andesite has been recorded from the large 

 Moon's Hill quarry, but a band of tutf dipping N.JST.E. at about 70° 

 occurs in the little excavation between the two main quarries. It is of 

 a rather coarse-grained type and closely resembles that interbedded in 

 the lower part of the andesite at Sunnyhill. 



In a paper already published an analysis of the Moon's Hill rock by 

 Mr. E. M. Lane was quoted. This unfortunately proved unreliable, and 



' Q.J.0.S., vol. Ixiii. 1907, pp. 217-240. 

 * Ibid., vol. Ixiii. 1907, p. 220. 



