xviii PREFACE. 



But the general question is not materially affected by the precise 

 epoch at which the lake of the Dead Sea became reduced to its present 

 dimensions. It is certain that in its present general form it must have 

 existed long before the glacial period. 



We know from the Norfolk chalk that in our own country a much 

 warmer climate existed previous to the glacial epoch ; and we have every 

 reason to infer that throughout the Northern Hemisphere a proportionate 

 increase of temperature prevailed. The Ethiopian fauna and flora, 

 admittedly more antique in type than the Palaearctic, must have had at 

 that period a more northerly extension than at present. The peculiarities 

 of the Dead Sea basin may be exactly paralleled with the traces of the 

 Spanish flora yet lingering on the south-west of Ireland. They were 

 probably synchronous in origin during the period of the great Meiocene 

 sea which covered the Mediterranean and Western Europe. The great 

 Meiocene land extended, as it would appear, south and west of this from 

 Southern Asia as far as the Azores, or, as Professor Forbes has suggested, 

 to the belt of Gulf Weed. There was then either continuous or closely 

 contiguous land, which would enable South-west Ireland to be stocked by 

 the flora of the Asturias, and Palestine by that of Abyssinia. The cir- 

 cumstances and chronology of these two isolated floras appear identical. 



But during this epoch, the whole country was doubtless covered and 

 peopled by the same forms, for which the warm climatal conditions were 

 suitable ; and the fauna and flora of Palestine were East African, either 

 identical or representative. The actual present refuges of the remnants 

 of this period, the nooks beside the Dead Sea, were still under water, for 

 they do not now rise 200 feet above the lake. Towards the close of the 

 Pleiocene period the area of the waters of the lake was diminished, as we 

 may see by the marl deposits leaning against the inclosing ranges. Then 

 supervened the glacial period. The climatal changes destroyed the mass 

 of existing life ; just as in South-west Ireland all the Spanish flora except 

 the hardiest, such as the saxifrages and the heath, have perished. 



But, as subsequently with the returning warmth in the British Isles, 

 the Scandinavian remnant continued to survive on the tops of the Scottish 

 mountains, so in the period of cold those species which were most 

 tenacious of life, retiring to the depression of the Jordan valley, then, as 

 now, proportionally warmer than the surrounding land, contrived to 



