SESSION 1898-99. xlix 



Field Meeting, 27th May, 1899. 

 BUSnEY, WATFORD HEATH, AND HARROW WEALD. 



The Geologists' Association has lately set apart a few excursions 

 each year especially for cyclists, and this was one in which 

 members of the Hertfordshire Society were invited to join. The 

 geological direction was entrusted to the llev. J. F. Elake, F.G.IS., 

 and the local arrangements were carried out by Mr. Hopkinson. 



The Bushey chalk-pit, east of the railway, which is just beyond 

 the edge of the London Tertiary basin, was first visited. It is 

 in the Upper Chalk, and altliough this formation is immediately 

 succeeded less than a furlong to the south by the Heading Beds, 

 the highest zone of the Chalk which occurs in this country is not 

 present. Although apparently conformable with the Chalk, the 

 lleading Beds are not reallj' so, overlapping ditfercnt members of 

 it, and thus showing that the Tertiaries were deposited upon the 

 denuded surface of the Secondary rocks. Above the Chalk is some 

 pebble-gravel, and above that there is brickcarth in one part of 

 the pit and yellow sand in another. Mr. Blake pointed out 

 the purity of the sand and clay (brickearth), which he thought 

 indicated that neither bed had been brought from a distance, 

 both being the relics of Tertiary strata formerly extending farther 

 northwards than they do at present. 



A short distance to the east of this pit, on the road to Bushey, 

 good exposures of similar gravel were seen in a new excavation, 

 and Mr. Blake inferred from the different levels of this gravel that 

 it was deposited after the main excavation of the valley. 



The Old Bushey and the New Bushey brickfields were then 

 visited, and in the latter the basement-bed of the London Clay 

 with a band of pebbles was seen. Underneath it are the sandy 

 clays of the Reading Beds with fragmentary traces of fossils, and 

 below these are ferruginous sands and pebbles worked for about 

 eight feet without getting to the bottom. In what a short 

 distance the character of the Beading Beds changes was shown by 

 the presence, on the south side of the pit only, of some curious 

 bands of very light-coloured rock looking in the distance almost 

 like chalk, which were found to be more compact and calcareous 

 than usual. 



Proceeding to Watford Heath, a collection of fossils made by the 

 late Mr. "W. T. Stone, who was a member of both the Hertfordshire 

 Society and the Geologists' Association, was exhibited by his son. 

 Many of them are local, but the collection is a very varied one. 

 Mr. Stone's most interesting discovery was that of the bone of 

 a monkey in the London Clay in his own brickfield. This was 

 determined by Professor Owen, to whom it was sent, to belong to 

 Uyracotherium leporinum. Here is exposed the pebbly basemeot- 

 bed of the London Clay from which were obtained the numerous 

 sharks' teeth and oyster-shells which had just been seen, and a few 

 fossils were found in it. The underlying sands are much more 

 largely developed here than at either of the Bushey pits, and they 



