392 Henry Woodward and W. Davies — 



in every stage of growth, rarely broken or rolled, and (land and fresh- 

 water) shells occur in abundance." Prof, Morris cites as from Ilford, 

 Cyrena trigonula (flnminalis), Pisidium amnicum, Unio pictorum, 

 Succinea oblonga, Helix Jiortensis, H. hispida, Limncea auricidaria, 

 ' L. peregr-a, Planorhis corneus, Paludina impura [op. cit. p. 544:). We 

 have not been able to discover where the specimens once forming 

 Mr. Gibson's collection are now preserved. 



The pit to which Sir Antonio Brady's attention has been mainly 

 directed, and from which nearly all his magnificent series of Mam- 

 malian remains have been obtained (and which now form part of 

 the National Collection in the British Museum), is known as the 

 Uphall Brick-field, and is situated on the right-hand side of the lane 

 leading to Barking. The ground forms a low terrace, bordering the 

 small Eiver Roding on the one side, and on the other it slopes 

 gradually down to the Thames. The height of the surface of the 

 ground at the pit is about 28 feet above the Thames H. W. M. 

 (Prestwich, Geol. Mag. 1864, Vol. I. p. 245). 



Probably no independent geological investigator, since the early 

 days of Buckland, Trimmer, Prestwich, and Morris, has paid such 

 careful attention to the structure of the Thames Valley, and of its 

 contained deposits, as Mr. Searles V. Wood, jun., F.G.S. Numerous 

 papers on this subject have been communicated by him to the 

 Quarterly Journal of the Geological Society, and to the Geological 

 Magazine. Writing thereon in 1866 (Geol. Mag. Vol. III. 

 p. 59), Mr. Wood observes : "The Brick-earth of Ilford, both that 

 of Uphall and that of the London- road Field, is a deposit underlying 

 the Thames gravel and unconformable to it." He also speaks of it 

 as anterior in date to the similar deposit of Grays, which likewise 

 contained Cyrena fluminalis, and other purely freshwater shells. 



In a letter to one of the authors (dated March 1st, 1874), Mr. Wood 

 writes : — " When I wrote the paper in Vol. III. (1866), I was under 

 the impression that though the Grays Brick-earth was clearly newer 

 than the main sheet of the Thames gravel (it forming distinctly a 

 terrace beneath it), the Cyrena Brick-earth of Ilford, and of Crayford 

 and Erith was anterior to, and passed underneath it. Some year 

 or two afterwards, however, I satisfied myself that this was an 

 error as concerned Crayford and Erith, and I wrote a letter to the 

 Geological Magazine (Oct. 10, 1868, Vol. V. p. 534), directly to 

 acknowledge this, 



•' The Ilford bed lying flush with the gravel sheet of that part of 

 Essex does not present the means of determination by section, but 

 I cannot doubt, however, that it is identical in age with the Cyrena 

 beds of Grays, Erith, and Crayford. 



" Such being the case, so much of the section No. 3, given at p. 61 

 of the Geological Magazine, 1866, Vol. III., as shows this Brick- 

 earth (x 4') as underlying the gravel [x 4"), is incorrect 



" The subject, however, is obscure, and while the Brick-earth at 

 Ilford, Grays, and Erith lies low, and forms a lower terrace to the 

 main sheet of the Thames gravel, it rises at Crayford to a greater 

 elevation, nearly 80 or 90 feet in parts, and forms a liigh terrace 



