,«,,. CLIMATE OF EUROPE. 429 



probably come from the Channel Islands and the coast of Brittany ; 

 one block of granite is probably from Cornwall. This fact of the 

 transportation of large erratic blocks for distances of at least a lum- 

 dred miles, shows that the temperature of the water in the spring, 

 though sufficiently high to dislodge the ice, was yet too low to melt 

 it rapidly. Even with a strong wind a flat mass of shore-ice would 

 take several days to cross the Channel. 



To compare this ancient ice-laden English Channel with existing 

 seas, it is necessary to travel northward, till we cross the isotherm 

 of 32° P., and are near the Arctic Circle. The English Channel, 

 being almost land-locked, no cold current like that of Labrador can 

 have had much influence on the temperature of the water. It is 

 possible, however, that the Channel was then much less salt and 

 froze more readily, but even in that case the winter temperature can 

 scarcely have been less than 20° lower than at present. 



Turning next to the evidence yielded by the marine fossils, we 

 are still unacquainted with the arctic species of the south of England. 

 The deposits which probably contain them are, unfortunately, 

 beneath the sea-level, and we are unable, till a marine fauna is 

 obtained, to speak confidently of the temperature of the water, or to 

 say whether it was salt or brackish. The shores of the North Sea, 

 however, yield much more satisfactory evidence ; for at Bridlington, 

 in Yorkshire, the Boulder Clay contains some included shelly masses 

 with the most intensely arctic marine fauna yet found in Europe. 

 Indeed, this fauna is as thoroughly arctic as any now living in the 

 Arctic Regions, and must have flourished in a sea whose temperature 

 was little above the freezing-point. The fauna of the " Bridlington 

 Crag " does not, however, mark the maximum intensity of the cold, 

 for the Till in which these shelly masses are embedded indicates a still 

 lower temperature, which caused solid ice to fill the whole of the 

 North Sea, and to plough up the marine clays previously deposited. 

 As far as the evidence will allow us to judge, the North Sea, then 

 as now, was a few degrees colder than the English Channel. No 

 trace of ancient glaciers has yet been found on the shores of the 

 Channel. 



Carrying our investigations further south, we find in France few 

 indications as to the temperature of the sea during any part of the 

 Glacial Epoch. In the Mediterranean region, however, certain 

 upraised sea-bottoms on the flanks of Mount Etna yield the evidence 

 for which we are searching, for they indicate by their included fossils 

 a temperature a few degrees — perhaps 5° — lower than that of the 

 present sea. Of course, it is not certain that these Sicilian deposits 

 were laid down during the greatest intensity of the cold ; still the series 

 of Pliocene and Pleistocene strata seems there to be complete, and 

 careful search has not led to the discovery of any fossil fauna of 

 more boreal character in other parts of the Mediterranean basin. If 

 no indications of greater cold are to be found in the ancient marine 



