btitcrops, and so on, scientists are now looking for suitable explanations 

 for this subaerial exposure, or successive exposures, of the shelf. 

 Glacio-eustatic and tectonic explanations are both favoured, and a whole 

 new field of instructive research is now opening up. 



These two schools, therefore, thanks to the localities of their active 

 protagonists, have more or less become associated to-day with Britain 

 and America versus continental Europe. 



Since Johnson's influence, for innumerable well- justified reasons 

 in other connections, has been widespread in North America, his theory 

 of marine abrasion has there become accepted almost without question. 

 It is fortunate, however, that doubts have also been expressed on that 

 continent. Wentworth (1927), as a result of careful studies in Hawaii, 

 came to the conclusion that marine erosion cannot be a factor in pene- 

 planation, only subaerial erosion could perform this colossal work. 

 As a result of these and other researches considerable doubts are 

 nowadays being expressed on the matter. Attention has also been drawn 

 to another great fundamental weakness in all Douglas Johnson's coastal 

 work, his omission to recognize fully the ever-riding control of eustatic 

 changes which in Pleistocene and Recent times gave rise to multiple 

 oscillating strand-levels (Shepard, 1937). Johnson (1933) made exactly 

 the same error as many others in the Pacific in mistaking the 10 ft. 

 eustatic bench as a storm-wave platform ; this is the same bench that 

 is so commonly found all around closed bays where storm-wa\'es 

 never reach. 



In conclusion, to summarize these remarks, we have made a protest 

 against accepting the dogma laid down in many of the standard English 

 and American text-books, following the teachings mainly of Lyell and 

 Douglas Johnson, which appear, thanks, no doubt, to the geological 

 constitution and geographical positions of the British Isles and the 

 rugged coasts of New England, to have grossly exaggerated the forces 

 of mechanical marine erosion and ignored the processes of subaerial 

 and chemical decay in the formation of coastal benches or terraces. 

 The works of European physiographers and those of New Zealand have 

 been sedulously disregarded in this connection. 



Finally, we deduce that the submerged and terraced shelf regions 

 of the Pacific and other oceans are not the result of mechanical erosion 

 operating to wave-base, but were cut subaerially and in the inter-tidal 

 belt during periods of low eustatic sea-levels (or tectonically elevated 

 continental rims) . The short time that has elapsed since that last great 

 emergence has prevented the accumulation of more than a thin veneer 

 of post-Glacial sediment. 



Bibliography 



Bartrum, J. A. (1916) : High-water Rock-platforms : A Phase of Shore-line 

 Erosion. Trans. N.Z. Inst., Vol. 48, pp. 132-34. 



(1926): " Abnormal " Shore Platforms, /owm. o/ Geo/., Vol. 34, pp. 793-806. 



— (1935) : Shore Platforms. Rept. Aust. &- N.Z. Assoc. Adv. Sci.. Vol. 22, 



p. 135-143. 



Bell, J. M., and Clarke, E. de C. (1909) : The Geology of the Whangaroa Sub- 

 division, Hokianga Division. New Zealand Geol. Siirv., Bull. No. 8, (n.s.), 1 15 pp. 



Bourcart, J. (1938) : La marge continentale. Essai sur les regressions et trans- 

 gressions marines. Bull. Soc. Geol. Fr., 5 ser., Vol. 8, pp. 393-474. 



Chamberlin, R. T. (1930) : The Level of Baselevel. Journ. of Geol., Vol. 38, pp. 

 166-173. 



Daly, R. A. (1920) : A Recent World-wide Sinking of Ocean-level. Geol. IMai;., 

 Vol. 57, pp. 246-261. 



356 



