446 ME. T. V. HOLMES — SECTIONS ON THE NEW [Aug. 1 894, 



But since April 29th the cutting had been widened and sloped, and 

 though plenty of material such as I have mentioned could be seen, 

 the boundaries of the channel, and its relations to the London Clay 

 and the gravel, had been utterly obscured. However, there seemed 

 to be traces of Boulder Clay near the channel, and, on walking 

 southward, we discovered on the western side of the cutting, at a 

 distance of rather more than 100 yards north of the Brentwood 

 Road, a considerable mass of Boulder Clay traceable horizontally 

 for more than 30 feet in the sloped side. It was in every respect 

 average Boulder Clay, like that seen at Hornchurch, and in it we 

 found a piece of Elmeridge Clay containing Lucina minuscula. 

 Similar fragments were seen in the Hornchurch cutting. This 

 Boulder Clay was on precisely the same level as that at Hornchurch, 

 and was similarly covered by gravel belonging to the Thames Valley 

 system. It was nearly 1| mile north-west of the Hornchurch 

 Boulder Clay. 



The relations between the Boulder Clay and the silted-up channel 

 could not be ascertained, as the cutting had been sloped, and 

 they appeared in different parts of it and not in contact. But 

 Mr. Whitaker was disposed to think that the silty material was 

 probably of Glacial age. 



The finding of the Boulder Clay at Hornchurch left the nature of 

 the hollow in which it had been deposited an entirely open question. 

 The additional Boulder Clay of the Romford cutting at precisely 

 the same level, and also covered by gravel of the highest, and pre- 

 sumably oldest terrace of the Thames Valley system, tends to show 

 that both were deposited in a broad valley belonging to some 

 drainage-system more ancient than that of the present Thames. It 

 appears to me that considerable light may be thrown on the probable 

 course of this ancient drainage-system by a brief investigation into 

 the distribution of the Boidder Clay towards its southern limits, and 

 by the leading features in the physical geography of the district. 



North and north-west of Romford a tract of high ground, rising 

 in places to a height of more than 300 feet above Ord. dat., lies 

 between that town and the valley of the Roding. Towards the north- 

 east, from "Warley through Billericay and Danbury, and in Tiptree 

 Heath, north of the Blackwater, we have also an elevated district. 

 However, along a line nearly parallel with that from Warley to Dan- 

 bury, but from 3 to 4 miles southward, we find a belt of low-lying 

 country, mostly less than 100 feet in height, and much of it below 

 50 feet. South of this lowland tract there is more high ground at 

 Laindon Hills, Hadleigh, Rayleigh, and Althorne, with a general 

 trend nearly parallel with those of the areas of high and low ground 

 just mentioned, though the Thames has now caused a breach of 

 continuity between Laindon Hills and Hadleigh, and the Crouch 

 has made a similar breach between Rayleigh and Althorne. 



On comparing maps showing the geology with others illustrating 

 the physical geography of the district, we find that the Boulder Clay 

 comes as far south as the edge of the high ground between Warley 



