PRESIDENTIAL ADDRESS. 553 



Of these, the most important is a marine deposit containing a moUuscan fauna 

 of southerly faciei, which occurs on the coast of Sussex near Selsey. The case 

 for its inlcrglacial age has been stated by my colleague, Mr. Clement Keid,' who 

 observed numerous large erratic bonlders resting on a floor of Eocene beds in a 

 temporary exposure on the foreshore, and infers that these boulders represent a 

 period of glacial conditions anterior to the deposition of the bed containing the 

 temperate-climate shells, while a later period of glaciation is inferred from the 

 presence of the ' Coombe-rock,' or chalky rubble, overlying the shell-bed. This 

 interpretation of the section has, however, already been challenged by Professor 

 P. F. Kendall.'- The erratics are not seen to pass under the clays with southern 

 mollusca, as there is a gap of about half a mile between the two deposits, so that the 

 succession cannot be proved by direct superposition. But Mr. Reid urges that 

 * another method is available : to observe the occurrence of material derived from 

 the one stratum and redeposited in the other.' ' No fragments of southern mollusca 

 have yet been found in the erratic gravel,^ but the clays with southern mollusca 

 often contained redeposited erratics. The gravel with erratic hlocks is, therefore, 

 the older of the two.' The bed overlying the shelly deposit also contains erratics, 

 and these, too, Mr. fteid considers to be ' redeposited ' ; but it appears to me that 

 the grounds for this inference are insufficient. By Godwin-Austen,* who had 

 previously described the section, it was considered that the horizon of the boulders 

 was above the shell-bed; and, since the shelly deposit itself does not appear to 

 exceed a few feet in thickness, it is probable that heavy stones dropped on the sea- 

 floor by floating ice would embed themselves in the shelly mud. 



Mr. Reid's suggestion that the shell-bed may represent a warm interglacial 

 epoch newer than the glaciation indicated by the Chalky boulder-clay, and there- 

 fore newer than the so-called ' middle glacial ' of Northern England, or than the 

 Helvetian Epoch of Professor Geikie's scheme, adds further confusion to the 

 issue : and the presence of estuarine and freshwater deposits on the same coast, 

 at West Wittering and at Stone, in Hampshire, also regarded as belonging to the 

 same interglacial episode, raises additional difficulties. 



Without entering at length into the matter, I can oidy state that in my 

 opinion, after full consideration of the records, these South Coast sections do not 

 afford definite proof of a mild interglacial episode. 



Some Deposits above the Boulder-clays. — The freshwater deposits at Hoxue,^ 

 in Suffolk, and at Hitchin, in Hertfordshire,^ classed by Mr. Reid as interglacial, 

 belong to a different category. They occur within the region of actual glaciation, 

 but in both cases it has been proved by Mr. Reid that the beds overlie the Chalky 

 boulder-clay ; and there has been no subsequent glaciation of the district. iVt 

 Hoxne, however, though not at Hitchin, the remains of arctic plants are found 

 in one part of the series, overlying deposits containing temperate plants. It is to 

 be noted, however, that several of the temperate plants occur also in the arctic 

 plant-bed, but are supposed to have been derived from the older deposit. 



Under the usual classification of the field-geologist, the whole series would be 

 regarded as late-glacial or post-glacial. At any rate, being above the Chalky 

 boulder-clay, they cannot belong to the supposed middle glacial, or Helvetian 

 Epoch ; and as the arctic plant-bed of Hoxne is classed by Mr. Reid'' as ' Late 



' ' On the Pleistocene Deposits of the Sussex Coast.' Quart. Joitrn. Geol. Soc, 

 vol. xlviii. (1892), pp. 344-61. See also The Origin of the British Flora (London, 

 1800), chap. iv. et seq. 



■ ' The Cause of the Ice Age.' Trans. Leeds Oeol. Assoc, pt. viii. (1803), p. G4. 



' Godwin-Austen, however, found southern shells in the Pholas-borings which 

 Mr. Reid assigns to the supposed glacial deposit : iifra cit. 



* R. Godwin-Austen ' On the Newer Tertiary Deposits of the Sussex Coast.' 

 Qiiart. Journ. Geol. Soc, vol. xiii. (1857), pp. 40-72. 



* ' Report of Committee on Relation of Palasolithic Man to the Glacial Period.' 

 Sep. Brit. Assoc, for 1896, pp. 400-415. 



« 'The Paleolithic Deposits at Hitchin and their Relation to the Glacial Epoch.' 

 Proc. Boy. Soc, vol. Ixi. (1807), pp. 40-49. 



' ' Origin of the British Flora,' si/jtra cit., p. 53. 



