880 REPORT— 1898. 



-where it opens out on the floor of the deep ocean at a depth of about 1,500 fathoms. 

 The slope of the escarpment varies considerably, but is occasionally almost vre- 

 cipitous, as, for example, off Cape Ortegal. From its base stretches the gently 

 sloping floor of the abyssal ocean formed of foraminiferal ooze, as determined by 

 Dr. G. C. Wallich and the ' Challenger ' Expedition ; thus the escarpment serves to 

 separate the region of the calcareous floor from that of the platform composed of 

 mechanically constituted materials. That it was formerly a land feature is proved 

 by the presence of river channels and deep ravines or canons once connected with 

 the streams which drain the adjoining lands. 



3. Submerged River Channels and Canons. — By means of the soundings the 

 courses of several rivers can be clearly traced, commencing at or near the shores of 

 the neighbouring lands, and generally becoming more determinate as they approach 

 the edge of the grand escarpment, through which they descend between precipitous 

 walls of rock, some thousands of feet in depth, towards the floor of the abyssal 

 ocean. Amongst those especially remarkable are the channels which drained the 

 Irish Sea and English Channel, the positions of which have been indicated by 

 several observers, including Mr. Godwin-Austen, Prof. Rupert Jones, Prof. Boyd 

 Dawkins, and Mr. Jukes-Browne ; but it does not appear that they recognised the 

 fact that they are traceable down to depths of over 1,000 fathoms where they cut 

 through the great escarpment. Besides the channels of some British rivers, those 

 of the Loire, the Adour, Las Cubas, the Douro, and Tagusare very clearly defined, 

 as the contours are traceable for miles inwards from the margin of the escarpment, 

 indicating canons of great depth, that of the Adour being traceable from the mouth 

 of the existing river to its opening on to the floor of the deep ocean at a distance 

 of 60 miles and a depth of 1,500 fathoms.^ In some cases the rivers have had double 

 channels when crossing the escarpment. 



4. Sea-stacks and Isolated Mocks.- — In addition to the above features, instances 

 occur of huge sea-stacks or isolated bosses of rock rising from very deep water. 

 One of these occurs off" the north coast of Spain, and has an altitude of over 6,000 

 feet. In general form it was similar to the great bosses which rise from the waters 

 on the coast of Scotland, such as the ' Bass Eock,' ' Rock of Dumbarton Castle,' 

 and ' Ailsa Craig,' but was vastly greater in dimensions than any of these. Un- 

 fortunately we are unable by means of soundings to determine the composition of 

 such masses, but they are probably formed of some excessively hard material, such 

 as felstone, basalt, or other volcanic rock able to resist the assaults of the ocean 

 waves for a longer period than the adjoining masses. 



General Conclusion. — It will be evident that the features above described — the 

 submarine escarpments and river channels — must have been formed, the one by 

 wave action along rising or subsiding land surfaces, and the other by river erosion 

 during a period of emergence of the whole region. It is only under sub-aerial 

 conditions that such escarpments and river channels could have been formed ; hence 

 we are driven to the conclusion that the eastern side of the North Atlantic was 

 upraised to the extent of 9,000 or 10,000 feet at a very recent period. This 

 deduction is in harmony with that arrived at by Spencer, Upham, and other 

 American geologists, and forces us to the conclusion that the whole area of the 

 North Atlantic was a land surface to the depth of 10,000 feet at a very recent 

 period. The author has pointed out how such an uprising of the lands must have 

 aflected the climatical conditions, resulting in a general lowering of the tempera- 

 ture ; and in connection with the alteration in the course and temperature of the 

 ' Gulf Stream ' must have brought about conditions over the northern hemisphere 

 such as those which are inferred to have been in force during the Pleistocene or 

 Glacial period.- 



' M. Elisee Reclus has recognised this profound canon, but is altogether at a loss 

 to account for its origin. 



= 'Another Possible Cause of the Glacial Epoch,' Trans. Ticto}-ia Institute (l8dS). 



