H. H. Hoicortli — Traces of a Great Post-Glacial Flood. 555 



Just as misleading as to apply the term GlaciaL period to a period 

 when the land was occupied by the Fig and the Hippopotamus, and 

 the adjoining rivers by the Cyrena fluminalis. The molluscan fauna 

 of the Glacial period proper must be sought for in the Pala^ocrystic 

 Sea, and not in the always open North Atlantic. My own view is 

 that when the Glacial period proper was current, the conditions were 

 such as to make life virtually impossible in the districts where it 

 prevailed, and to drive living things, both animals and plants, else- 

 where. This a priori view is amply confirmed by the geological 

 evidence. 



Mr. Crosskey, in the Transactions of the Glasgow Geological Society 

 vol. ii. p. 47, speaking of the section at Lochgilphead, says, "Nothing- 

 can be more striking than the change from no life in the Boulder- 

 clay to abundant life in this bed (2, the shell-bed) immediately 

 on it." In the section in the Kyles of Bute, he says, "Fossils might 

 appear to an inexperienced observer to be in the Boulder-clay, when 

 they really occur at points where the fossiliferous bed is in imme- 

 diate contact with it" (id. p. 49). Again, one of the conclusions to 

 which he calls special attention, as the result of his examination of 

 the beds in question and others, is, "That the Boulder-clay proper, 

 at the base of the series, is destitute of fossils. A number of cases 

 in which fossils were said to occur in the Boulder-clay have beeu 

 examined, and it has been found that they were either beneath it or 

 that an upperdrift has been confounded with it" [id. p. 51). Again, 

 speaking of the beds at Paisley, Messrs. Crosskey and Eobertson say, 

 " In the Boulder-clay itself we have not yet succeeded in this 

 neighbourhood in finding any signs of life" (id. vol. iii. p. 337). 

 Speaking of these same Paisley beds. Dr. Fraser says, "Underlying 

 all was the old Boulder-clay or Till, the conditions of which were 

 altogether unfavourable to life. It represented a cold, bleak, and in 

 part tumultuary period" (id. vol. iv. p. 178). 



I select these passages because they are in the first place from 

 writers who are deservedly esteemed authorities on these beds, and 

 secondly because they refer to a district where their true sequence 

 and history, as it seems to me, can best be followed. 



Let us now proceed. When the glacial conditions proper abated, and 

 a condition of things ensued which was rather that of the seas about 

 Southern Greenland and Iceland than of the Palseocrystic Sea, molluscs 

 of a certain tyjDe no doubt invaded the more suitable waters. We 

 actually find in Britain and in Scandinavia that the azoic Boulder-clay 

 proper is followed by beds containing Northern forms of shells, and 

 that as we trace these beds upwards we gradually meet with a molluscan 

 fauna of a more and more temperate character. The series can be well 

 studied, as has been shown by Mr. Crosskey and his colleague, in the 

 Clyde and neighbouring beds. This position is so Avell accepted now as 

 to be hardly arguable, and is well stated by Mr. Crosskey in the follow- 

 ing sentence, "The fossiliferous clays and sands belong to several ages ; 

 and the fauna usually catalogued together must be separated into 

 distinct groups, each referable to its own bed, and having its own 

 place in the gradual transition from a severely arctic to a more 



