SEGTIOIfS BErWEEN UPMI^^^TER AND ROMFOED. 369 



apparently of Boulder Clay somewhat rearranged and without 

 boulders, and having a thickness of 1 or 2 feet. At a point between 

 50 and 60 yards east of the second or more westerly bridge, the 

 Boulder Clay abuts against the London Clay, which rises to a higher 

 level and is less covered by gravel at this end of the cutting than at 

 the other. Thus this mass of Chalky Boulder Clay, which extends 

 along the cutting for a distance of 300 yards, owes its preservation 

 to its deposition in a slight hollow on the surface of the London 

 Clay. And as the cutting will very shortly be entirely obscured 

 through the sloping and turfing of its sides, it is perhaps worth 

 noting here that the space within which Boulder Clay can now be 

 seen nearly coincides with that between the 100-feet contour-lines. 

 It comes in about 30 yards east of the contour-line nearest the road, 

 and ends between 50 and 60 yards east of the other. The thickness 

 attained by the Boulder Clay does not, probably, anywhere much 

 exceed the 15 feet actually measured, as London Clay rises, for a 

 space of 4 or 5 yards, to a height of between 2 and 3 feet above the 

 bottom of the cutting, towards its centre. 



This Boulder Clay is in all respects like a typical example of that 

 common in Essex. The great majority of the stones in it are 

 chalk or flint, the latter being both worn and unworn. During a 

 visit to the cutting on February 6th last Mr. Herries found a 

 quartz-pebble and a small fragment considered by Mr. Whitaker 

 to be Lower Greensand. And the foreman of navvies at work 

 there brought me one day a. glacially-scratched lump of dark 

 bituminous shale from it containing small shells, which Mr. H. B. 

 Woodward identified as Kimeridge Clay, the shells being Luc'ina 

 minuscula.^ 



A glance at the map of the Geological Survey will show that, 

 except in this cutting, Boulder Clay has never been seen in conjunc- 

 tion with the deposits of the Thames Valley, either north of Romford 

 in Essex or in the neighbourhood of Finchley in Middlesex, the most 

 southerly spots at which it has been known. In the Bomford dis- 

 trict the nearest point at which it appears is about three miles north- 

 east of this Hornchurch cutting. It there rests on the London Clay, 

 around the house called Maylands, a little east of the Ingrebourne, 

 and appears to come down some distance below the 200-feet contour- 

 line, though the great mass of the Boulder Clay north of Eomford 

 lies above that level. We thus find at Maylands a slight tendency 

 towards the still lower level of the Boulder Clay in the Hornchurch 

 cutting. 



Readers of the very interesting chapter in Mr. Whitaker's latest 

 Memoir ^ on the Literature of the Thames Valley Drift must have 



^ On the visit of the Geologists' Association to tbis cutting on March 5th, 

 Mr. Robertson, the engineer of the line, very kindly showed us a collection of 

 the most interesting specimens obtained from the Boulder Clay. They included 

 many lumps of Kimeridge Clay, some examples of GryfhcBa dilatata from the 

 Oxford Clay, and a vertebra which had been determined by Prof. Seeley as 

 plesiosaurian. 



^ ' The Geology of London and of part of the Thames Valley,' vol. i. p. 3f 

 London, 1881). 



