2 THE NEW RAILWAY BETWEEN UPMINSTER AND ROMFORD. 



north and south of the Mardyke, consists of old river-gravel, except 

 where some bare Chalk appears near West Thurrock. This old 

 river-gravel lies indifferently on the Chalk or Tertiary deposits, and 

 that on each flank of the Mardyke valley evidently once formed a 

 continuous sheet. Between a point rather more than a mile south 

 of the Mardyke, and another between Stubbers and North 

 Ockendon, this gravel, along the course of the railway, has a surface 

 level varying between sixty and seventy feet above Ordnance Datum. 

 In the cutting at and south of the road between Manor Farm and 

 North Ockendon, brick-earth, clay, and sand appeared, as also in 

 others northward towards Cranham Hall. Between Cranham Hall 

 and Upminster the railway is on an embankment. Between the 

 Mardyke and Upminster the cuttings are shallow, seldom, if ever, 

 exceeding ten to twelve feet in depth, and in my journeys along the 

 line I never saw the underlying London Clay in this part of the 

 course of the railway except for a distance of two or three hundred 

 yards close to the Mardyke valley. In short, the sections afforded 

 by the cuttings revealed nothing but the gravel and brick-earth 

 -shown on the map of the Geological Survey. 



A glance at the map just referred to makes it obvious that the 

 Thames in this south-western corner of Essex has once flowed by 

 Hainault Forest, Romford, Hornchurch, and North Ockendon to 

 Hangman's Wood, Mucking, and Stanford-le-hope — a course much 

 more northerly than that of its present channel. And examination of 

 the tract of river-gravel, which remains as a record of this fact, shows 

 that it consists of flat ground very gradually increasing in height as 

 we recede from the present Thames and approach the undulating 

 London Clay, which lies beyond the gravel plain. Thus we find 

 that the surface of the gravel of Hainault Forest, of the ground 

 close to but north of Romford, Hornchurch, and Upminster, and on 

 the eastern side of North Ockendon, has a height above Ordnance 

 Datum of loo feet, or a little more. If we look for gravel 

 averaging sixty to seventy feet, we find it occupying a belt of ground 

 roughly parallel with that just indicated, but nearer the Thames, at 

 Chadwell Heath, south of Hornchurch and Upminster, and west of 

 South Ockendon. Similarly, areas below fifty feet are those around 

 Ilford, Dagenham, Barking, and Rainham. These facts all point to 

 the conclusion that the Thames once flowed at a height of loo 

 feet or more above its present level, and some four or five 

 miles northward of its present course ; and that the river has 



