Iviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



made by that accurate traveller, Seetzen, who, in 1807, described 

 plateaux of basaltic lava as capping limestone hills at some distance 

 from the lake. Prom some of the higher points, it would appear 

 that coulees have flowed downwards through the valleys ; and whilst 

 the volume of these igneous rocks seems to be small as compared 

 with what obtains in the country further northward, it is important 

 to observe that their eruption must have been long posterior to the 

 formation of the deep chasm, as proved by their flowing along the 

 deep gorges which debouch upon its waters. 



M. Lartet has also done good service in tracing and describing 

 with distinctness the strata of fine sediment which were deposited 

 by the lake when it stood at a level higher by above 300 feet than 

 at present. Eurrowed and torn asunder by the rains and torrents 

 of the wet season, these friable beds of marl and gypseous clay are 

 seen, at various places near the borders of the Dead Sea, standing 

 in cones and ridges and ragged plateaux, often of the most fantastic 

 forms. In the peninsula of Lisan they were studied to the greatest 

 advantage, but nowhere yielded a single fossil ; and it may perhaps 

 thence be fairly concluded that, even at that remote period, when 

 the waves of the " salt sea" beat against the sides of the valley of 

 the Jordan at least halfway up to Tiberias, its waters were already 

 so far saturated with chlorides and bromides as to be unsuitable for 

 the maintenance of animal hfe. 



Change of Climatal Conditions. — Is the cause of this once very 

 different surface-level of the Dead Sea to be sought in a former 

 more abundant influx of waters resulting from a moister climate, 

 or in a less vigorous evaporation than at present, or in both com- 

 bined? and what has been the source of so great a change of 

 climate between that time and our own? M. Lartet suggests that 

 the high water-level probably belonged to the Glacial period, when, 

 as we have learned from Dr. Hooker, glaciers lay upon the flanks 

 of Lebanon, and the temperature of Southern Palestine must con- 

 sequently have been low enough to be consistent with a heavy rain- 

 fall and little evaporation. Should the startling novelty announced 

 by Dr. Praas be confirmed, of the traces of glaciers in Sinai, it 

 would be a matter of high interest to connect them with the same 

 period. It is argued also from the dimensions of the various water- 

 courses which open upon the vaUey, and which are now in ordinary 

 spring or summer weather mostly dry, that they must have been chan- 

 nelled out by powerful streams which have long ceased to exist ; but 

 in the absence of trustworthy accounts of the amount and volume of 

 these streams in the winter season, those who are acquainted with 

 the transformations connected with southern climates, and have 

 seen the Jiumaras of Sicily, the ramblas of the Alpuj arras, and the 

 wadis of i^orth Africa, will hesitate before concluding the inability 

 of the present rainfall to cut down the ravines on a large scale. 

 It is nevertheless in favour of this argument, that several, at least, 

 of these outlets are by no means worn down to the present level of 

 the lake, but open upon it in the abrupt shores at such a height 

 above its surface as to give the impression that the excavating action 



