464 



MAMMOTH AND OTHER REMAINS IN ENDSLEIGH STREET. 



Square the gravel attained a thickness of 9 feet, the overlying sand 

 about 2 feet, and the yellow clay over 4 feet. The ' made ground *" 

 here averaged about 6 feet in thickness. The lower part of the clay 

 (b) in the section facing this page (fig. 4, lY. on the Map) was very 

 calcareous here, and continued so for some distance southwards in 

 Gordon Square. Between the loamy sand and the clay, and in places 

 in the latter, there was also a gravelly clay ; in this I found many 

 fragments and several well-preserved specimens of shells which had 

 evidently been derived from the London Clay. This find is important, 

 not only as proving that much of this yellow clay must have been 

 derived from the London Clay, but also as showing, from the con- 

 dition in which the specimens were found, their occurrence at one 

 place only, and at that place in fair abundance, that they must have 

 been transported to this spot by ice. 



An examination of the fragments and pebbles in the gravelly clay 

 in which the shells were found leads to the conclusion that they 

 might have been derived from the combined denudation of Chalk, 

 London Clay, and a deposit resembling in a marked degree the gravel 

 described by Prof. Hughes in Hertfordshire as the ' gravel of the 

 Upper Plain.' ^ Quartz-pebbles are unusually plentiful in it, gene- 

 rally small, but frequently from half an inch to an inch across. 

 There are also quartzite pebbles, and worn fragments of chert, 

 ragstone, &c. 



The marked resemblance between the gravelly part of this deposit 

 and the gravel occurring as enclosed patches in the brown clay with 

 * race ' at Finchley and Hendon presented itself very forcibly to my 

 mind, and a careful comparison made since has proved that they are 

 almost identical in composition. The patches in the brown clay at 

 Pinchley and Hendon could hardly have been deposited otherwise 

 than as frozen masses, and I think the evidence here points to the 

 means of transport as having been ice, with a subsequent slight re- 

 adjustment of the materials by water -action. The presence of so 

 much calcareous matter, of so many quartz-pebbles, and of many 

 unbroken shells would indicate the direct transport to this spot of 

 the material. 



The shell most plentifully found is a Pectunculus, derived from 

 one of the basement-beds of the London Clay, and as these beds are 

 nowhere exposed in the immediate neighbourhood, but occur on the 

 Hertfordshire plateau, in places, under the Plateau Gravel, it seems 

 reasonable to suppose that the shells were transported directly with 

 the gravel to the spot in Gordon Square where they are now found. 

 It is well known that they are very brittle, even in the original bed, 

 hence a very slight amount of water-action would have entirely 

 shattered them, and no complete valves could have been found at any 

 distance from the parent bed. Some of the ' race ' found so abun- 

 dantly in parts of the clay is probably due to the decomposition of 

 septaria from the London Clay, but it seems equally probable that it 

 has in part been derived from dissolved Chalk. 



1 Quart. Journ. Geol. Soc. vol. xxiv. (1868) p. 284. 



