﻿part 1] 



IGNEOUS ROCKS OF THE BRISTOL DISTRICT. 



31 



is concealed 1 as far as the eastern margin of Weston Woods. On that 

 margin, at a distance of 160 to 190 yards north of the Milton Hill Lodge, its 

 •outcrop can be fixed exactly, and in a field west of the four cross-roads at 

 Milton Hill the debris of it is abundant. At this point it appears to be 

 shifted about 200 yards northwards by the Milton Hill fault, for the next 

 point determined upon the outcrop is a small pit, now a pond, observed by 

 Professor Lloyd Morgan some years ago. The easternmost exposures occur 

 in the sides of a pond near Florence Cottage, 700 yards east of the Milton 

 Hill fault. No evidence of its existence farther east has been found.' 



Since Dr. Strahan re-examined the ground, two further exposures 

 have been made : — 



1. In May 1911 trap was exposed in erecting a cistern at the 



spot marked 98 on the map (fig. 6, p. 30) about 250 yards 

 north-north-east of Milton-Hill Lodge. The exposure is 

 now, however, completely obscured. 



2. In 1912 the southern branch of the cross-roads at Milton 



Hill was widened. At first the lava was exposed in a small 

 road-cutting, but this is now hidden by a wall. Poor ex- 

 posures are still visible at the side of the road. Several 

 slightly-varying types of lava are seen, but no signs of tuff — 

 in fact, the only evidence for the existence of tuff on Milton 

 Hill is an observation made by Prof. Lloyd Morgan in 

 1894 at a spot near the Kew Stoke road, now the site of a 

 small pond. Excavations were undertaken during the year 

 1915 at this locality. At the point 102 immediately south- 

 west of the pond, highly- vesicular lava closely resembling 

 that of Florence Cottage, and unlike any other rock hitherto 

 exposed on Milton Hill, was reached at a depth of about 

 5 feet. In a second hole immediately west of the pond 

 nothing in situ was reached ; and the tenant informed me 

 that, when the pond was made in 1904, surface-soil to a 

 depth of 12 or 14 feet was penetrated. A careful search 

 in the neighbouring fields, though yielding much lava, did 

 not provide any tuff. These observations, though unfortu- 

 nately not confirming- Prof. Lloyd Morgan's record of tuff, 

 in no way invalidate it. The spot where he observed the 

 tuff is exactly on the line where one would expect it to 

 occur : namely, between the limestone and the basalt. Its 

 non-occurrence as surface-debris, and the great thickness of 

 soil overlying it, are clearly due to its softness. The net 

 result of the observations made by various geologists on 

 Milton Hill shows that the lava has an outcrop about 

 200 yards wide, which, with a dip of 23° or thereabouts, 

 would imply a thickness of about 150 feet, and that it 

 forms the whole of the strip of well-cultivated ground 

 between Furze Close and the road leading from Milton Hill 

 to Kew Stoke. 



1 Not only is the lava unexposed, but (despite careful search) I have been 

 unable to find any debris. 



