164 PROF. E. HULL^ ON THE SUB-OCEANIC RIVER VALLEYS, ETC. 



the Institute in a recent paper ; for, with elevated and consequent 

 glacial conditions as well as during the subsequent subsidence, 

 there would be converging on the ocean shore opposite to where 

 is now the bight of the Bay of Biscay, vastly greater erosive power 

 than at any place further north. 



Evidences of the upheaval of the whole of the Iberian peninsula, 

 and not merely of its western side, are not wanting. Professor 

 Hull gives some facts as to the sea bottom of the Mediterranean 

 opposite the mouth of the River Ebro. It seems to me, however, that 

 the Ebro Channel, before the subsidence and the formation of the 

 present delta, took a southerly direction. There is a very decided 

 indentation of the continental platform, having a northerly 

 direction from nearly opposite Valencia, and extending northwards 

 between the Columbrates Isles and the coast at Castellon. It 

 points directly to the Ebro at Tortosa before the delta is reached 

 by that river. The present mouth of the Ebro at the Cabo de 

 Tortosa I regard as having a quite different direction and being 

 consequent on the formation of the delta of which the Cabo de 

 Tortosa is the most eastern point. Opposite to the delta of the 

 Ebro the sea bottom descends from 200 metres depth to 1,000 metres 

 in a distance of 10 kilometres, but this is at a distance of from 90 

 to 100 kilometres from the old coast line on the landward side of 

 the delta. 



An explanation of the glacial conditions that undoubtedly 

 prevailed over vast areas of the northern hemisphere during 

 Pleistocene times, must be regarded as a most important geological 

 result, and believing that continental elevation will afford this 

 explanation, and that the investigations of Professor Spencer and 

 Professor Hull furnish cogent evidence of such elevation, I think 

 they deserve the hearty thanks of all geologists. 



