46 MR. G. BARROW OX THE CORRELATIOX OF THE [vol. lxXV, 



The course of these deposits has been traced from the neighbour- 

 hood of London, both on the east and on the west sides of the 

 Misbourne, near Chalfont St. Giles ; and at Hampstead Heath the}' 

 rest upon the Bagshot Beds, while at Barnet and Stanmore they 

 are on the London Clay. Recent work has proved the presence of 

 these beds between Chorley Wood (north-east of Rickmansworth) 

 and the Misbourne valley. At Chorley Wood tkey rest on the upper 

 part of the brilliantly-coloured marl near the top of the Reading 

 Beds, while farther west, at the Vache, they rest on a slightly lower 

 horizon. It was a little to the north of this that the locality was 

 found where they rested on the ' sarsen ' of the Reading Beds. 

 Mr. J. F. N. Green and the writer had the rare good fortune to find 

 a large block of sarsen with the base of these high-level gravels 

 firmly cemented to its upper surface. The gravel here consisted 

 mainly of the typical small white quartz-pebbles. A little farther 

 north the gravel occurs near the base of the Reading Beds, and it 

 Avas pointed out that these gravels must occur still farther north, 

 resting directly upon the Chalk, but that the outcrops were probably 

 concealed under Drift of some kind. 



The gravels of Little Heath, Berkhamsted. described above, are 

 ■ clearly an example of the occurrences predicted; they are typical 

 of the deposits containing the ' neighbouring ' small pebbles of 

 white quartz and lydite from the Lower Greensand, but no far- 

 travelled stones. Moreover, the deposit occurring at a higher level, 

 the local stones in the gravel are much bigger than in the area at a 

 lower level and farther south. 



It has now been clearly proved that the small quartz-pebbles 

 entered the area about Chorley Wood, and Chalfont, through the 

 Wendover gap, the old floor at 500 feet above sea-level being in 

 part still preserved beneath a thick coating of material mainly 

 composed of large fragments of unworn flint. It is more likely 

 that the quartz-pebbles at Little Heath came either through the 

 gap at the head of the Bulbourne valley (near Tring), or through 

 that at the head of the Gade, probably the former. 



A point of especial importance in connexion with these gravels 

 resting on the Chalk, is that the High-Level Gravels north of the 

 Thames are now brought into line with those occurring in a similar 

 position south of the Thames. This leads to the conclusion that 

 these deposits are really allied to the Lenham Beds, but possibly 

 are somewhat younger. 



DlSCUSSIOX OX THE TWO FOREGOIXG PAPERS. 



Dr. R. L. Sherlock congratulated Mr. Gilbert on bringing 

 before the Society this account of a remarkable section. 

 Mr. Gilbert had devoted much time to a thorough investigation 

 of his subject, and deserved the Society's thanks for a plain 

 statement of facts. 



In the five years 1910-1914 the speaker surveyed, on the 6-inch 

 scale, some 300 square miles of the counties of Buckinghamshire 



