294 TYNEDALE ESCABPMEXTS ; 



will further illustrate and more deeply impress. There can be 

 no doubt in any candid mind, that branching systems of valleys, 

 large and small, have in the main been carved out by such 

 agencies, dii'ccted, and possibly aided, by others. 



I have taken rivers first as productive of effects hitherto more 

 successfully estimated than those of any other denudant. Let 

 me now say a little about the sea, — a denuding force of vast im- 

 portance, though restricted to the borders of the land. Every sea- 

 girt cliff is the vertical scar that marks the work of a "great 

 horizontal saw," of which, indeed, each billow may be said to be 

 a tooth.* This vertical scar is only, of course, the index to work 

 in progress ; the sawn surface, as well as the debris, is hid under 

 water. Where, however, receding tides bare a portion of it, 

 we often find an approximate flat, or as Ramsay has called it, a 

 ''plain of marine denudation ;" and, comparing this plain with the 

 tumbled outlines of the countiy above the cliff, it seems possible 

 to say that the sea is more of ix planing tool than any other geo- 

 logical tool we know. Its importance, therefore, as probably the 

 explanation of such wide-spread denudation as the shorn summits 

 of Northumbrian escai'pments testify, is e^'ident. It is well 

 known that in parts of the East Coast of England the sea is saw- 

 ing its soft cliffs back at fi-om two to four yards in the year, — 

 that within historic memory populous and fertile tracts have been 

 beaten down and submerged. "We may take it as certain, that 

 if not interfered with by subterranean movements, — by elevations 

 or subsidences, the sea would convert Britain into a submerged 

 plain, and deposit its sediments over the scars of upturned strata. 



The sea, maker of uneven plains, — of sawn suriaces, and river 

 systems, cutting them up, are the two great denuding agents of 

 wholesale change ; and it is unnecessary to go beyond them. In 

 the broad aspect, however, the latter is servant to the former. 

 " All go unto one place" — the sea level ; and whatever may have 

 been the myriad forms of the land between elevation as a raised 

 plain of nj urine denudation and destruction to a plain again — the 

 latter is the ultimate stage. f If slicing thi rcforc has been done 



• Dr. James Golkic. 



t On thl« hulijict the render U roferrcd to rrofcssor Raoisny't tine book on the Pby- 

 oical nooUvy unci Oeo^rnpliy of nrltniii. pp. ■'i41. 49G. Ath ICdIliun. 



