High- Level Sands and Gravels near Berkliamsted. 663 



The Chalk flints, which are scattered in such profusion over all 

 parts of the surrounding country, are almost entirely absent, while 

 the small pebbles of white quartz and lydite, so abundant in the 

 underlying gravel, are seldom met with. It seems probable that 

 the ice must have derived its materials from a distant area. The 

 deposit is very persistent, often cutting into, and disturbing the 

 beds beneath. 



On the west side of the pit, underlying the pebbly clay, is a 

 disturbed mass of Glacial sands and clay, of a very miscellaneous 

 character. The whole deposit is suggestive of an englacial origin. 

 It is introduced in the form of a wedge or V-fault cutting into the 

 beds beneath, the pressure having come from the west. These 

 Glacial beds were traced to a depth of about 20 feet, when the 

 workings in this part of the pit were discontinued. At the apex 

 of the wedge towards the east, the beds against which it had been 

 forced showed signs of considerable disturbance. 



No deposits have been found in any way corresponding to the 

 stratified Glacial sands and gravels which are so extensively deve- 

 loped at Bedmond, about 5 miles away to the south-east, and contain 

 a large percentage of rocks foreign to the district. 



Beneath the Glacial beds is a stratified deposit of dark reddish- 

 brown mottled loamy sand. The entire deposit is banded with 

 very fine lines or partings of the grey clay. Some are ripple- 

 marked, and others are covered by sun -cracks and apparent rain- 

 spots, indicating that each separate layer became exposed to the 

 air after deposition. The sun-cracks are very persistent through- 

 out the deposit, and are suggestive of genial climatic conditions. 



There is almost invariably a sharp break between the loamy 

 sands and the underlying gravels. 



The gravels have often an undulating surface, even where the 

 bedding of the sands is horizontal, and strongly resemble a series 

 of tidal beaches. 



The laminae of the loamy sands in the hollows of the beaches 

 do not always follow the contour-line of the beach, but are 

 deposited more or less horizontally, occasionally with a slight local 

 unconformity. It seems probable that the water gained sudden 

 access through one of the beaches at a distance, depositing first the 

 heavier burden of sand, and then the lighter parting of clay in 

 suspension, this operation being repeated by successive storms or 

 high tides leaving the sands high and dry during the intervals. 

 Hence the sun -cracks and rain -spots. 



The fact that the surface of the clay-partings never shows signs 

 of erosion, either from water or from subaerial agencies, suggests 

 that the various layers of the sands were deposited at fairly frequent 

 intervals, and in quiet water. 



The underlying gravel-deposit consists almost entirely of Reading 

 pebbles and waterworn flints in approximately equal quantities, 

 with an occasional pebble of pudding-stone from the Reading 



