310 TECTONIC GEOLOGY 



Recently Professor Gregory * has made some very important suggestions in 

 regard to a re-classification of coast types. He states ("Scientia," op. cit., p. 7), 

 "I pro23osed in 1908 to subdivide the Pacific type into two varieties — the primary 

 Pacific tyj^e along the outer edge of the fold mountain chains, and the secondary 

 Pacific or sub-Pacific type, where the coast is less directly connected with the 

 border chains of the Pacific, but is due to subsidences within the mountain chains." 



He next states (p. 48) : " Primary Pacific coasts are determined by the proximity 

 of long lines of fold mountains, to the trend of which the coast is in general parallel. 

 The mountains bounding them are of comparatively young geological age. Over- 

 thrusts and overfolds, if present, are mostly directed towards the ocean. 



" Secondary Pacific or sub- Pacific coasts are due to the subsidence of basins on 

 the inner side of mountain chains along coasts of the primary Pacific type. 



" They are frequently bordered by active or recent volcanoes. The oldest rocks 

 usually occur along the coast, and are followed by younger rocks farther inland ; 

 except where horsts project into the sea, the coast-line is approximately parallel to 

 the grain of the adjacent country." 



Gregory states further (p. 52) : " Professor Suess, however, in his last volume, f 

 remarks that the coast of South Victoria Land recalls the fractures of East Africa 

 rather than a Pacific arc. The points on which he lays stress are the horizontal 

 position of the sandstones, the wide distribution of gneiss and granite, and the 

 contours. I fail, however, to see any particular resemblance between this coast and 

 that of the fractured area of Eastern Africa. There the land is a high plateau, com- 

 posed mainly of Archaean rocks ; it was flanked at intervals along the coast by 

 marine Mesozoics ; its volcanoes are inland upon the ^ilateau, and not at its foot ; 

 and there are no representatives along the coast of the lower Palaeozoic slates of 

 Cape Adare or of the Archseocyathus limestone of the Beardmore Glacier. The 

 coast of South Victoria Land seems to agree both in the character of its rocks and 

 their .arrangement with Eastern Australia, and should accordingly be assigned to 

 the secondary Pacific type." 



On page 54 he concludes : " The information now available shows that South 

 Victoria Land is more similar in structure to Eastern Australia than to New 

 Zealand. Hence it appears most probable that the continuation of New Zealand 

 and of the primary Pacific coast lies through King Edward VH. Land towards 

 Graham Land. Hence I should be disposed to classify the coasts of Antarctica 

 as shown on Fig. 8, South Victoria Land being of the secondary Pacific type, 

 the line from King Edward VH. Land to Graham Land of the primary Pacific 

 character, and the remaining coasts of the Atlantic type." 



* Structiu'al Geographj', 1898, p. 61, § vii. 



Scientia, vol. xi., sixth year (1912), xxi. pp. 36-63. "The Structural and Petrographic Classifica- 

 tions of Coast Types." J. W. Gregory. 



t "The Face of the Earth," vol. iv. pp. 293-294. 



