90 



ON THE MOLLUSCA OF SOME HOLOCENE DEPOSITS OF THE 

 THAMES RIVER SYSTEM. 



By A. S. Kennard, F.G.S., and B. B. Woodward, F.L.S. 



Bead IZth March, 1908. 



I. TJXBRIDGK, MlBDLESEX. 



The Holocene deposits of the River Colne, though extensive, are 

 practically unknown, and the only description of them was that given 

 by J. Allen Howe in 1903.' The valley of the Colne undoubtedly 

 resembles those of the Lea and the main stream of the Thames itself 

 in that it furnishes evidence of the presence of an old and now buried 

 channel. Unfortunately we have no details as to the depth or exact 

 situation of this channel, but, judging from the main stream, the 

 depth would probably be about 35 feet at Uxbridge. The sections 

 examined are, as so often the case, very different in character. The 

 first one is close to the present bed of tlie river, where extensive 

 excavations have been made for gravel. The section is — 



1. Peaty earth 2-6 feet. 



2. Gravel 10-20 „ 



The peaty earth contains in places a little shell-marl, and the upper 

 part yielded sixteenth century pottery, bones of ox, horse, sheep, pig, 

 dog, and part of a single shed antler of fallow-deer. 



According to information supplied hj the workmen, this bed is 

 thickest near the river and gradually thins out towards the eastern 

 side of the valley. The gravel is of Pleistocene age, and probably 

 belongs to the fourth terrace, i.e. a stage later than Crayford. The 

 watei'-level is about a foot below the top of the gravel, and the gravel 

 is excavated mechanically under water until the London Clay is 

 reached. On the top of the gravel and beneath the alluvium an 

 enormous number of worked flints, probably of late Pleistocene age, 

 was found. 



The other sections were first noted by our friend Mr. A. Loydell, 

 who most kindly informed us of them, and placed the extensive 

 collection of Mollusca which he had made at our disposal. These 

 sections are situate at the foot of the eastern side of the valley just 

 north of the main road, and were made during the construction of 

 a railway siding. The deposit here is a sandy clay with molluscan 

 remains scattered throughout, and but little peaty matter or gravel 

 is seen. These beds yielded no evidence in the shape of human 

 relics as to their age. 



From these deposits we are now able to record fifty-nine species of 

 Mollusca, viz. — 



1 Proc. Geol. Assoc, vol. xviii (1903), pp. 188-190. 



