576 DR. H. HICKS ON SOME RECENTLY-EXPOSED SECTIONS 



and it contained, in addition to numerous unrolled white-coated 

 flints, many distinct bits of chalk. Until rccenth' this was the 

 only perfectly satisfactory instance which had come under my 

 observation in Hendon of a typical chalky Boulder-clay similar to 

 that which is so well known at Finchley. 



That the Upper Boulder-clay must have been spread out very 

 generally over the Hendon plateau, and by the same agency as 

 that which deposited it on the areas farther north, is now certain. 

 What is here mostly found, however, is a brown or yellowish- 

 brown clay like that which at Whetstone and Finchley usually 

 occurs below, but also frequently passes into and occupies the 

 position of the more distinctly chalky clay. In some places it is 

 very stony, but more often the fragments and pebbles are only 

 scattered about in it. In parts also there is an almost entire absence 

 of pebbles and rock-fragments. 



In a drain recenth' made in the Green Lane on the Hendon 

 slope, looking towards the Brent Valley, and 175 feet only above 

 Ordnance datum-line, a brown clay was exposed which yielded many 

 fragments of a hard white chalk, the largest piece being about 

 2 inches long. The clay was also seamed in all directions with 

 decomposing carbonate of lime (" race "). The occurrence of this 

 Chalky Boulder-elay at so low an horizon is interesting also as 

 proving conclusively that the Brent Valley had been in the main 

 scooped out previous to the deposition in it of the newer Glacial 

 deposits. Moreover, on the Finchley side of the valley there is 

 equally good evidence, for the Boulder-clay is found there also at 

 many points considerably below the 200-feet contour-line. 



In an extensive pit, opened in the year 1889, near the centre of 

 the plateau upon which Hendon is situated, and about | mile S.E. 

 of the exposure referred to in Parson Street, an average thickness 

 of 7 feet of a brown clay with bluish streaks was exposed, resting 

 upon about 8 feet of sand and gravel. This pit is about 245 feet 

 above Ordnance-datum, and has been dug in a field opposite West 

 View, between New Brent Street and Heriot Boad. When the 

 underlying floor of London Clay was reached it was found to 

 'be very irregular in character, and resting on this floor were 

 large masses of angular sarsen-stones, in some cases showing what 

 appeared to be distinct traces of ice-markings. As the pit was 

 enlarged, it was seen that the Upper Boulder-cla}^ sometimes 

 reached downwards through the Sands and Gravels until it had 

 completely penetrated them and touched the underlying floor of 

 London Clay. In a deep drain which was carried from this pit in 

 a S.W. direction for about 130 yards for the purpose of drawing 

 off the water, several of these channels filled with Boulder-clay 

 were met with, the Sands and Gravels lying between in a com- 

 paratively undisturbed condition. These channels varied from a 

 few feet to several yards in width. In the pit and drain the floor 

 of London Clay was found to be very uneven, rising up here and 

 there in hillocks, and as the Gravels were seen to pass horizontally 

 across these banks, it became evident that such irregularities must 



