O THE NEW RAILWAY BETWEEN UPMINSTER AND ROMFORD. 



sible for the most careful observer to note, with any approach to 

 accuracy, the hmits of a terrace of river deposits cut in so soft a 

 formation as the l,ondon Clay. But the straight streets and open 

 squares of the district south of Endsleigh Gardens, in which these 

 excavations were made, afford much better views than usual of the 

 shape of the ground. And they reveal the perfect flatness of an 

 old river terrace, averaging originally about 75 feet above Ordnance 

 Datum, though now with a surface elevation of five or six feet 

 more, owing to the overlying " made ground." In short, the 

 appearance and position of this level tract seem to me to suggest 

 nothirlg whatever but an old terrace belonging to the present 

 Thames Valley system. 



Then, if we consult the Geological Survey Map, we find that the 

 area between Euston Square and the river is coloured as one of old 

 river deposits, a little bare London Clay being shown here and there 

 along the course of a valley. Mr. Whitaker, in his memoir on the 

 " Geology of London and of part of the Thames Valley,"^ has the 

 following remarks on the boundary of the River Drift between the 

 Serpentine and the Fleet : 



• " The boundary-line follows the course of the Serpentine Brook 

 northward as far as the Great Western Railway, whence eastward by 

 Paddington to the southern part of Regent's Park it is doubtful. In 

 Mr. Mylne's map the gravel is coloured farther to the north than on 

 the Survey map, perhaps rightly.* From Regent's Park the 

 boundary runs eastward to Euston Square, beyond which the tunnel 

 of the Metropolitan Railway is in London Clay." x\nd in another 

 part of this memoir (vol. ii., p. 321), we learn that at Gower Street 

 Station and at Euston Square, on the Metropolitan Railway, there 

 was at the first-named spot, " sand and gravel with yellow clay," 

 thirteen to seventeen feet, resting on the London Clay, and at 

 Euston Square gravel and sand up to eight feet. The made ground 

 at the surface varied from four to seven feet in thickness. Indeed, 

 in spite of the obscurity arising from the buildings and the " made 

 ground," which cover the surface, the Geological Surveyor has been, 

 on the whole, by no means at any special disadvantage hereabouts, 

 owing to the record of the deep and continuous sections on the 

 Inner Circle Railway. Thus the general evidence bearing upon the 

 affinities of the beds overlying the London Clay around Endsleigh 



3 Vol. i., p. 398. 



4 Mr. Whitakei- holds that where the boundaries of a superficial formation are doubtful, it is 

 better to err on the side of under-estimating the area it covers, than of over-estimating it. 



