SUEFi-CB-DEPOSITS OP THE EALING DISTRICT. 193 



action of springs. In this paper I gave reasons which convinced 

 me that these deposits of gravel and foreign rock-debris were due 

 to the action of ice which had stranded and melted there, and thus 

 been caused to deposit its burden of glacial detritus. These high- 

 level gravell)- deposits afford evidence of the last period of emergence, 

 especially when viewed in conjunction with similar formations 

 which are found surmounting Horsington Hill (25<^ ft. 0. D.) to the 

 north, and other elevations in Middlesex ; they indicate, moreover, 

 the period when the wider hollow between the chalk hills of greater 

 height was submerged. 



Castlebar Hill (167 feet high), which may be taken as an illus- 

 tration of other hills, presents us with evidence of a character quite 

 different, and which, so far as I know, has never been described before. 

 On the western slope, near the junction between the Edgehill and 

 St. Stephen's roads, there has been exposed a thick bed of gravel, 

 sand, and loam, the approximate height of which is 160 feet. The 

 section shows that the lowermost deposit is almost entirely composed 

 of completely rolled pebbles, which are intermixed with a few frost- 

 split black pebbles, and that above this is sand ; the abraded angular 

 flints which usually form so large a proportion of a fluviatile de- 

 posit are absent ; above the sand is a finer gravel containing a 

 larger proportion of small angular fragments, which is associated 

 with thin cross-bedded layers of sand and blue clayey loam, strongly 

 indicative of varying currents. The argillaceous seams generally 

 dip to the west in conformity with the present incline of the hill. A 

 similar gravel occurs further east, nearly on the same level, at the 

 junction of the St. Stephen's and Castlebar roads, so that this gravel 

 probably continues over the rise of the hill which intervenes : 

 these deposits overlook the Thames Valley on the south and the 

 lower ground to the north. Similar gravels occur on the north 

 slope of the hill, and hence appear to be out of the range of what 

 have hitherto been regarded as bench-gravels. Thus, in one section 

 made, about 2()0 feet distant from the trees which mark the former 

 entrance to the late Duke of Kent's Park, several feet of gravel with 

 much clay and ferruginous sand was seen at about 150 ft. above 0. D. ; 

 while a little lower down, near Castlebar Court, a similar formation 

 occurs. Gravel is met with at other places along this north slope. 



What has hitherto been considered true bench-gravel (i.e. the 

 usual stratified beds and brick-earths) commences in this district on 

 the flanks of the hills at 130 feet, and is bounded northwards and 

 upwards by London Clay, or stiff brick-earth much resembling it. 

 This clay-covered area, which extends north from near the Longfield 

 avenue to the beach-like gravels at the summit of the hill, contains 

 pot-holes or depressions filled with gravel, which, as it would seem, 

 indicate the former continuity of the higher and lower gravels ; 

 similar pot-holes of gravels were noticed between the AValdeck lload 

 and Cleveland Koad, again connecting the terrace-deposits with the 

 beach-like formation, &c., at the latter. 



I have a well-formed implement which was found in gravel to 

 the north of the Longfield Avenue (125 ft. above 0. D.); it was 



