Bordering the British Isles. 355 



miles we have a remarkably uniform succession of features, consisting 

 of a gently sloping submerged terrace, stretching out from the coast 

 to a variable distance, but which, on reaching a depth of 100 to 200 

 fathoms, breaks off in what would be a grand escarpment of 7,000 to 

 8,000 feet, if viewed from the outer ocean. Such regularity of 

 features through so great a distance cannot be regarded as accidental; 

 it points to uniformity of cause and mode of production. It is to 

 a terrestrial surface we must have recourse for the explanation of the 

 physical conditions here described. We are familiar with examples 

 of plateaux bounded by escarpments leading down into plains both 

 in the British Islands and in other countries. We have a familiar 

 example in the Cotteswold Hills of Gloucester and Somerset ; in the 

 range of the Jura; in the range overlooking the Delta of the Nile 

 above Cairo. All these terraced escarpments have been formed over 

 the surface of emergent lands; they are absolutely terrestrial, not 

 oceanic in their origin ; and in ascribing a similar origin to those 

 here under consideration, we are only drawing a logical deduction 

 from the premises laid down. In a word, this grand terraced 

 escarpment of the British Isles must have been formed during 

 a period of emergence of the whole region to an extent of several 

 thousand feet above the surface of the ocean, as it is at the present 

 day. Professor James Geikie has recognized the generally abrupt 

 descent of the continental plateau, but does not appear to have 

 recognized that such features must have had a terrestrial origin.^ 



IV. Submerged River Channels. — The views I have just expressed 

 receive remarkable confirmation from the existence of old river 

 channels, which may be traced on the Admiralty charts by the 

 soundings. It will be evident that during the period when the 

 British platform was in the condition of a land surface, the rivers 

 descending from the adjoining land, as well as the rain which fell 

 upon its own surface, must have had outlets to the ocean towards 

 the west ; and we are, therefore, led to inquire, are such outlets, 

 in the form of river channels, to be recognized by the soundings ? 

 I am able to give a very decisive answer in the affirmative to this 

 question. Notwithstanding that the submerged lands around the 

 British Isles have for thousands of years been covered by water, 

 more or less loaded with sediment, and during the later glacial 

 stages laden with icebergs and floes carrying stones and mud, 

 two old river channels, at least, can be clearly traced — one draining 

 the lands now occupied by the waters of the Irish Sea, and the other, 

 by those of the English Channel. The courses of these old rivers 

 are indicated by slightly irregular depressions in the soundings, 

 varying in depth from 2 to 20 fathoms below the general levels 

 adjoining, but they become remarkably accentuated on approaching 

 the margin of the great escarpment, where they are converted into 

 gorges or cailons bounded by precipitous walls of rock, and traceable 

 down nearly to the base of the escarpment. 



1 Address to Geographical Section, Brit. Assoc, 1892: Proc. Roy. Geog. Soc, 

 Sept., 1892, p. 639. The aiithor, however, clearly describes the mode ot formation 

 by marine action on emergent lands of such plateaux as the British platform, p. 6-14. 



