THE NEW RAILWAY P.ETWEEN UPMINSTER AND RO.MKORD. 3 



during many ages been occupied in deepening its valley, and in 

 gradually taking a more southerly channel. This last-named 

 tendency of the Thames is still more obvious between London and 

 Windsor, in the still greater breadth there of the gravel plain on the 

 northern bank of the present stream. 



The embankment mentioned as existing on the railway between 

 Cranham Hall and Upminster rests on London Clay, lietween 

 Cranham Hall and the Mardyke (as already observed) the line 

 traverses a continuous gravelly or loamy plateau ; but from Cranham 

 Hall to Romford the gravel or loam covering the flat-topped higher 

 ground is cut through, and the London Clay exposed, in the valleys 

 of the Ligrebourne and other streams which intersect the route. 



In the cutting at and west of Upminster Station, London Clay 

 was seen capped by a variable amount of gravel and loam. These 

 surface deposits were seldom more than six to seven feet thick, their 

 base being from eighty-five to ninety feet, and the surface from 

 ninety to a little over loo feet above Ordnance Datum. The 

 gravel hence to Romford belongs entirely to this highest and 

 oldest of the terraces of the Thames valley in this district. It was 

 noticeable that in this cutting it was often seen to lie in festoon-like 

 hollows on the surface of the London Clay, which sometimes even 

 formed the surface for a few feet between two of these festoons. 

 This mode of deposition is usually observed to be a characteristic of 

 these old river-gravels at all levels, wherever the junction with the 

 London Clay is clearly visible for any distarre. 



Crossing the Ligrebourne, we enter another cutting, the most 

 interesting and important along the whole line from Grays to Rom- 

 ford, though it has now been for some months sloped and soiled, and 

 yields no sign of its former attractions. About 250 yards east of the 

 church at Hornchurch the road to Upminster is crossed by otheri? 

 ranging north and south. About 400 yards north of this point of 

 junction is the cutting, extending mainly westward, and having a 

 total length of about 600 yards. Towards its two ends, only London 

 Clay capped by sand and gravel could be seen ; but in the ctntre, 

 where the cutting attains a depth of from twenty to twenty five feet, 

 a considerable mass of Boulder Clay was once visible, lying in a 

 hollow on the surface of the London Clay. It extended along the 

 cutting for a distance of 300 yards, and was in every respect tvpiral 

 Chalky Boulder Clay. Indeed, when I read a short paper before 

 the Geological Society on these se'lions between Upminster a:;d 



B 2 



