February 24, 1898] 



NA TURE 



403 



that the organisms lived in the positions where the shells are 

 now found. In some cases there are also fairly clear indications 

 that the deposits have been transported to fairly high levels by 

 ice which had passed over and scraped up materials from the 

 sea- bottom. 



It seems safer, at present, from the evidence which has been 

 brought forward of late years by so many competent observers, 

 to assume that towards the close of the Glacial period the earth- 

 movements produced changes only of a few hundred feet rather 

 than the greater depression and upheaval suggested by the earlier 

 geologists. 



Early Pleistocene Conditions on the East Side of England. 



On the east side of England, as on the west, there were at 

 this time great plains, extending out from the valleys, and much 

 of the area now covered by the North 'Sea must have been dry 

 land where northern and southern animals commingled. That 

 this was the case is shown by the finding of their remains in 

 close association in the hysena-den at Kirkdale and in other 

 caverns in Yorkshire. Prof. Phillips many years ago came to 

 the conclusion that the Kirkdale Cave was occupied in the 

 " pre-GIacial condition of the land which is now Yorkshire," 

 and he also maintained that the lowest Hessle Gravels which 

 rest upon the chalk, and which contain mammoth and other 

 remains, and are covered by Boulder-clay, are pre-Glacial in 

 age. 



Mr. G. W. Lamplugh's careful researches seem to show 

 clearly that the Sewerby Gravels, which have yielded so many 

 Pleistocene remains, are at the base of the glacial series in that 

 area. He says of the fauna at the base of the drift at 

 Sewerby :— " It is essentially the fauna of the Kirkdale Cave." ^ 

 In his conclusions, given in the same paper, when referring to 

 the physical conditions prevailing in the area during the formation 

 of the drift-deposits, he says : — "At a period not long anterior 

 to that of the glaciation of the coast, Flamborough Head was in 

 existence as a bold promontory jutting out into a sea whose 

 level was slightly above that of to-day. Most of the mammals 

 characteristic of the Glacial period were already living, and 

 tenanted the interior in large numbers. The climate was moist 

 and not very severe, the prevalent winds, as shown by the sand- 

 dunes of Sewerby, being from the west or south-west. After the 

 land had remained for a long time stationary, a slow elevatory 

 movement set in, and the climate became much colder ; so that 

 the Chalk-surface was disintegrated by frost and eroded by 

 sudden floods, which spread thick beds of muddy detritus over 

 much of the low or slightly sloping ground in the vicinity. 

 Meanwhile the bed of the North Sea was being rapidly filled 

 with ice through the great extension of the Scandinavian 

 glaciers, till at length the Scotch and Scandinavian ice coalesced, 

 and what remained of the North Sea was well-nigh ice-locked." 



Although some southern forms whose remains have been dis- 

 covered in the forest-bed on the Norfolk coast do not appear to 

 have reached much further north than that area, this does not, 

 in my opinion, make it in any way certain that even these were 

 not, in part at least, contemporaneous with the so-called mixed 

 early Pleistocene fauna of the more northern districts. It is also 

 an important fact that many of the most characteristic animals 

 whose remains have been discovered in the caverns in North 

 Wales and Yorkshire are now always included in the fauna of the 

 forest-bed. The position of the forest-bed of Norfolk under 

 high cliffs of Boulder-clay is also very similar to that of the 

 lower deposits near the entrance to the Vale of Clwyd, contain- 

 ing Pleistocene remains and trunks of trees in like manner 

 covered over by a great thickness of Glacial drift. It may also 

 be compared with the forest-bed in Holyhead Harbour, buried 

 under "stiff" blue clay," in which two perfect heads of the 

 mammoth were found when the excavations for the railway 

 were made in 1849. The tusks and molars were buried two 

 feet deep, in a bed of peat three feet thick, with stumps and roots 

 of trees. ^ 



It may be well to mention that the following mammals, whose 

 remains have been found in caverns in North Wales, Derbyshire, 

 and \'orkshire are now generally given as forming a part of the 

 fauna of the Norfolk forest-bed, and that several of them, such 

 as the glutton, musk sheep, and mammoth must be considered 

 typically northern animals. The list is taken from those pub- 

 lished by Prof. Boyd Dawkins or Mr. E. T. Newton, and there 

 are animals which may be classed as characteristic of arctic, 

 temperate, and hot climates. Animals whose remains have been 



1 Quart Joum. Geol. Soc, vol. xlvii. (1891). 



2 " Principles of Geology," Lyell, vol. i. (1867) p. 545. 



found in caverns in association with human implements, and 

 which are stated also to occur in the Norfolk forest-bed, viz. 

 Elephas antiquns, E. primigenitis. Hippopotamus amphihiiis, 

 Eqttus caballus. Sits scrofa. Bison, Ovibiis vioschatiis, Cerviis 

 elaphus, Cervus capreolus, Megaceros, Machairodus, Canis lupus, 

 C. vulpes, Hycena crocuta, Vrsus speUcus, Gulo luscus, Lutra 

 vulgaris, Arvicola amphibius. 



When the cold increased, the animals on the East coast, as on 

 the West side, were driven further and further south, and those 

 least able to bear the increased severity of the climate were the 

 first to migrate from the various areas. The southern forms may 

 consequently be looked upon, for the areas in which they have 

 been found, as the oldest fauna ; but it is reasonable to suppose 

 that they were contemporary with the more northern forms, 

 which at that time lived in other districts where the conditions 

 were more suitable to them. When the northern forms reached 

 the South of England, the conditions in and around the 

 mountainous districts were such that few animals could 

 remain there, as most of the valleys and plains had become 

 buried under ice and snow, and they would have to seek 

 feeding-grounds outside these areas. It is to this period that 

 we must assign the remains of the mammoth and rhinoceros which 

 are so abundantly found on the old land-surfaces on the north of 

 the Thames, usually hidden under great thicknesses of drift, as 

 in Endsleigh Street, and in other places in Middlesex. Here, 

 and in some areas further south, they could have lived during 

 most of the Glacial period until at last driven away, when the 

 valleys and plains became covered with vast sheets of water, due 

 in part probably to subsidence, but largely owing to the gradual 

 melting of the ice and snow further north. Whether the mammoth 

 and rhinoceros continued to live much longer in some parts of 

 the South and South-west of England there is very little evidence 

 at present to show. The supposition, however, held by some 

 that they returned to the glaciated areas after the Glacial period 

 had passed away does not seem to me in any way probable, for 

 hitherto their remains have only been found either under or in 

 the drift, and not above it, excepting when they have been 

 washed out from the earlier deposits. 



Summary. 



The evidence which has been obtained from ossiferous caverns 

 at high elevations in the glaciated areas shows conclusively that 

 the remains of the extinct mammalia found in them must have been 

 introduced before any of the Glacial deposits now in or upon 

 them could have been laid down, therefore either before or so 

 early in the Glacial period that there could not have been at the 

 time any considerable amount of snow on the neighbouring 

 mountains, or glaciers even in the higher valleys. 



From caverns in glaciated areas in North and South Wales, 

 where palseolithic implements have been found in association 

 with remains of the extinct mammalia, facts have been obtained 

 which make it certain that the implements were those of man 

 living at the same period as the extinct animals in those areas, 

 and therefore of pre-Glacial age. It has also been shown 

 that as the cold increased the higher valleys became filled with 

 glaciers, and the caverns became uninhabitable. That after- 

 wards, as the snow-line and glaciers descended lower and lower, 

 some of the caverns were subject to inundations, which not only 

 disturbed and rearranged the deposits previously in them, but 

 wholly or partially filled them up with local materials. That 

 in the Vale of Clwyd, North Wales, the local glaciers gradually 

 coalesced with those from the western and northern areas, 

 and a mixed material was distributed over the district to a 

 height of over 600 feet, burying the ossiferous caverns beneath 

 it. During this time also water re-entered some of the 

 caverns, redisturbing in part the earlier contents and depositing 

 some of the mixed drift over that previously in the caverns. 



While these caverns were occupied as dens by the hyaenas, 

 noithern and southern animals commingled in the valleys and on 

 the great plains reaching out from them to the area now covered 

 by the Irish Sea. 



From numerous examinations made of undisturbed Glacial 

 deposits in Wales, the North of England, and Scotland, it has 

 also been proved very clearly that the extinct mammalia, whose 

 remains are found in a.ssociation with the implements of Palaeo- 

 lithic Man in caverns, mu.st have lived there before those deposits 

 had been laid down, as their remains always occur at the base or 

 in the lower parts of the drift, and never above it. Further, 

 there is not a particle of evidence to show that the extinct 

 mammalia ever sevisited those areas after the close of the Glacial 

 period. 



NO. 1478, VOL. 57] 



