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



gravel and loam, lying here and there on the surface of rocks of 

 various ages, the evidence of any fossil remains they might contain 

 might give a presumption of more or less weight as to their affini- 

 ties. But where we have to consider a connected series of heds 

 like those of the Thames Valley, we become entirely dependent on 

 the stratigraphical evidence for information as to the persistence of 

 any given forms of life, and should not allow mere a priori assump- 

 tions as to their continued existence, or the reverse, to have any 

 influence whatever on our deliberations. 



My former paper on the sections seen on the New Railway from 

 Grays Thurrock to Eomford was read on March 9th, 1892. On 

 May 25th of the same year a very interesting paper, which I had 

 not the good fortune to hear, was read by Dr. Hicks: 1 and this, from 

 the conclusions favoured as to the age of what I take to be beds 

 belonging to the Thames Valley system, demands a brief discussion 

 here. "We may well congratulate ourselves that so important a 

 series of sections was brought under the notice of so eminent a 

 geologist as Dr. Hicks ; for, having been made in order to effect 

 improvements in the sewerage, their existence was extremely brief, 

 and might easily have been closed before any trustworthy recorder 

 had had an opportunity of noting their character. From the full 

 and well-illustrated account of these sections given by Dr. Hicks, 

 we learn that they varied considerably in detail. In each case there 

 was at the bottom an eroded surface of London Clay. Above this, 

 here and there, where the surface of the London Clay was concave, 

 was a thin stratum of dark clayey loam containing seeds, which bed, 

 Dr. Hicks remarks, " appeared to pass almost insensibly into what 

 was clearly deeply-stained London Clay with septaria." In this 

 dark loam some mammoth-tusks were found (22 feet below the 

 surface), also many seeds of plants living in marshy places or ponds 

 and (according to Mr. Clement Eeid) existing at the present time 

 from the Arctic Circle to the South of Europe. Resting either on 

 the London Clay or on the clayey loam was a bed of gravel of 

 variable thickness ; on the gravel, sand ; and on the sand, clay 

 with ' race,' flints, etc. The ' made ground < forming the surface 

 seems to have varied usually from 6 to 10 feet in thickness. 



The height of the surface where these sections occurred is about 

 80 feet above Ord. dat., or a few feet less if the ' made ground ' 

 be excluded. Any one who walks through the straight streets 

 and open squares of the district in which these sections appeared 

 cannot fail to notice the almost perfect flatness of the ground, which 

 much resembles that of a broad expanse of old river-drift. And as 

 consisting of a terrace of old river-deposits this district has been 

 mapped by the Geological Surveyors. 



Nevertheless, Dr. Hicks inclines to look upon these beds as 

 probably older than the Boulder Clay, because the gravel, sand, and 



1 ' On the Discovery of Mammoth and other Eemains in Endsleigh Street, and 

 on Sections exposed in Endsleigh G-ardens, Gordon Street, Gordon Square, and 

 Tavistock Square, London,' Quart. Journ. Geol. Soc. vol. xlviii. (1892) p. 453. 



