KENNARD : HOLOCENE NON-MARINE MOLLUSCA OP ENGLAND. 257 



a long interval is a common feature in many alluvial deposits, 

 especially in the lower Thames valley, so for my purpose I shall 

 only consider the first sequence. It is open to question whether 

 stages 7, 8, and 9 should be included in the Holocene. In these 

 matters it is always difficult to draw the division line. Stage 9 

 is certainly Pleistocene, and since the two succeeding stages are really 

 part of the preceding glacial period, I prefer to classify them with it. 



Stage 6. The lowest forest growth is well known and has been 

 recognized in many places in Northern Europe and in Ireland 

 (Proc. Geol. Assoc, vol. xxviii, 1917, pp. 144, 157). The well- 

 known deposit at Dogs Bay, West Galw»y, yielding the large and 

 heavy examples of Helix nemoralis, linn., is of this age. This form 

 has been named var. pura by Westertund {Verhandl. Zool.-Bot. 

 Gesell. Wierii vol. xlii, 1892, p. 34). The derivative examples of 

 this species found in the Neolithic flint mines at Grimes Graves, 

 Norfolk, also belong to this stage {Report of the Excavations at 

 Grimes Graves, 1915, pp. 220-3). To this period I would also assign 

 the lacustrine deposit at Perranzabuloe, Cornwall {Proc. Malac. Soc. 

 Land., vol. viii, 1909, pp. 247-50) and the remarkable chara deposit 

 at Haweswater, Silverdale, Lancashire {Journ. of Conch., vol. xi, 

 1905, pp. 147-51 ; and Lane, and Chesh. Nat., 1914, pp. 135-40 and 

 197-201), as well as many of the chara marls of the Fen Country 

 {Fenland Past and Present, p. 572). It may be noted that in this 

 country it was the late Dr. R. Munro, the able archaeologist, who 

 first pointed out the true age of the marl deposits from the molluscan 

 evidence, for he said, " The suggestion that the period of maximum 

 development of the freshwater testacea which produced the shell 

 marl deposits of Scotland correspond chronologically with that of 

 the forest growths is not therefore unreasonable " {Prehistoric 

 Scotland, 1899, p. 26). As already noted, lack of knowledge prevents 

 me from deducing accurately all the climatic conditions, but I can 

 assume that the summers were much warmer than the average of 

 to-day, probably resembling that of 1921, but with a greater rainfall 

 in the remaining seasons than in that year. 



Stage 5. The succeeding humid period is well represented in 

 England, and it may be called " the maximum development of the 

 damp-loving species ". Copford, Felstead, Chignal St. James, 

 and Shalford (Essex), Blashenwell (Dorset), Totland Bay (Isle of 

 Wight), Allen's Farm, Ightham, and the Neolithic grave at Cuxton 

 (Kent), the Cornish Towan deposits, Harlton (Cambridgeshire), 

 Wilstone (Hertfordshire), Grimes Graves (Norfolk), Wheatley 

 (Nottinghamshire), and many other Midland deposits may all be 

 assigned to this stage. There is no evidence so far as we are con- 

 cerned of the supposed colder phase No. 4, and it is probable that 

 it may represent the maximum of humidity (see Proc. Geol. Assoc. 

 Lond., vol. xxxiii, 1922, p. 142), and thus the stages 3, 4, and 5 

 would represent one phase in climatic change. 



C. E. P. Brooks has suggested that this stage practically coincides 



