

40 MR. C. J. GILBERT OX DEPOSITS OF HIGH-LEVEL [vol. lXXV, 



The gravel is also found in a field south- west of Little Potten 

 End and over a good part of Berkhamsted Common, at altitudes 

 varying, apparently, by at least 30 feet, the infilling sand and 

 small stones being always present. Where the sand-filling is of a 

 yellow tint, he always expects to find a deeper and richer deposit 

 of gravel. Mr. W. Humphrey's information is largely confirmed 

 from other sources. 



At Dwight's cottages at Potten End (see A on the map, p. 34), 

 Mr. J. Matthews (builder) says that he sank 30 feet into loose 

 gravel with sand — -similar to the Little-Heath gravel-beds — with- 

 out finding the bottom, and the cesspit has ever since effectively 

 drained into the gravel. 



The gardener of Mr. Xorman MacLehose, of Little -Heath 

 House, a short distance from the pit, states that in two exca- 

 vations in the grounds surrounding the house, they got to the 

 chalk at 18 feet (see B on the map, p. 34). In the water-cistern 

 it was all in the loose gravel (pebble-beds) and kept falling in. 

 In the dumb well about 25 yards away, the pebbles were almost 

 entirely in stiff clay — probably part of the Glacial beds — and 

 just above the Chalk they found four or five cartloads of loose 

 .gravel and sand (pebble-beds probably denuded by glacial action). 



At Mr. Spencer Holland's (Crossways), about 100 yards away, 

 and about 20 feet lower down the Hill (see C on the map, p. 34), 

 Mr. Matthews says that they had to sink 70 feet before Chalk was 

 reached. The upper part for 30 feet was pebbles in clay (Glacial 

 beds). About half-way clown, they went through 3 or 4 feet of 

 loamy sands, then the loose gravel (about 35 feet). 



The Origix of the Loamy Saxds axd Gravels. 



That these are marine deposits seems clear from the following 

 considerations : — 



(1) The distribution of the pebbles, with those larger and less worn at 



the bottom, and the tendency to become finer in the upper beds. 

 This quite accords with the behaviour of conglomerates at the 

 base of other and older marine formations (the Cambrian, for 

 instance). 



(2) The manner in which the pebbles are arranged in contact one with 



the other, the interstices packed with small pebbles and sand. 

 This is precisely the structure of modern tidal beaches and the 

 older marine conglomerates, but is not in my experience seen in 

 fluviatile or glacial gravels. 

 <3) The condition of the large flints, which show a complete gradation 

 from those almost unworn to well-rounded pebbles, similar to 

 the gradation found in beaches in which the materials are 

 immediately derived. 



(4) The nodings on the puddingstone pebbles and the worn portions of 



many of the larger flints, indicative of beach-hammering. 



(5) The presence in abundance of small quartz- and lydite-pebbles in the 



interstices between the bigger stones, which must have drifted 

 aljng the foreshore for a considerable distance. 

 <6) The contour and surface undulations of the gravel, so suggestive of 

 tidal beaches. 



