﻿part 1] IGFEOUS ROCKS OP THE BRISTOL DISTRICT. 



29 



border of Sir John's Wood, where the eastern end of a field 

 suddenly narrows, and is enclosed between Sir John's Wood on the 

 north and Round Wood on the south (see fig. 5). The exposures 

 in the hedge-bank continue for about 20 yards. At the western- 

 most point (70) compact trap was exposed after a small amount of 

 excavation, and the same rock is fairly well seen at the point 72 ; 

 farther east the rock becomes strongly amygdaloidal (73, 75). 

 Ten triahholes were dug in the wood and field adjacent to this 

 exposure. Of these 1, 2, 5, 6, 7, and 10 all exposed limestone 



Fig. o.—Sketch-mctj) showing the position of the trial-holes 

 at Limeridge Wood, TicTcenham. 



after passing through 4 or 5 feet of soil. No. 8 was carried 

 deeper, but nothing was found in situ. Nos. 3 and 4 exposed 

 trap, the rock 76, of which the silica and alkali content were 

 estimated (see p. 38), being obtained from trial-hole 3. In no 

 case was the contact between limestone and trap met with, and 

 no sign of alteration was seen in any of the limestone. Limestone 

 dipping at one point 28° west-south- westwards is exposed nearly 

 all along the hedge-bank in the lane on the south ; and it seems 

 clear that it completely surrounds the trap, which forms an oval 

 mass measuring not more than 60 by 25 yards. The field evidence 

 indicates that the trap is an intrusive mass. 



