96 C. Schuckert — Problem of Continental Fracturing 



and mountains of eastern Australia, while the rest of it has 

 sunk deep into the present Tasman sea. The other, or eastern 

 trough, which also appeared early in the Paleozoic, maintained 

 itself after this era in diminished extent throughout the Meso- 

 zoic and even into Pliocene time. This may be known as the 

 New Zealand geosyncline, a far narrower but longer one than 

 that of Australia; the shorter southern portion has now risen 

 into the mountains of New Zealand, while the much longer 

 northern part has apparently subsided to a depth of not more 

 than 9,000 feet, forming a submerged plateau upon which stand 

 the volcanic islands of the Kermadecs and the Tongas. 



Historical geology of New Zealand (see figs. 2 and 3). — In 

 the New Zealand trough there appear to be, according to Park, 

 no less than 45,000 feet of Paleozoic and 11,000 feet of Meso- 

 zoic sediments, all of which are apparently of marine origin. 

 These are coarse in grain and have much interbedded igneous 

 material, indicating that the adjacent lands were unstable and 

 repeatedly reelevated into high lands. There appear to be no 

 Cambrian or Triassic strata here, but the remainder of the 

 geologic column is as well represented by marine deposition as 

 is usually the case in geosynclines. There were at least four 

 times when the New Zealand trough was markedly subject to 

 folding and uplift ; these were toward the close of the Silurian, 

 Devonian, Jurassic, and Cretaceous periods. During the Ceno- 

 zoic, the New Zealand trough also appears to have, been in con- 

 tinuous subsidence from late Eocene into Pliocene time, when 

 about 9,000 feet of marine sediments had been laid down along 

 the eastern sinking margin. Late in the Pliocene there was 

 marked vertical uplift, probably as much as 4,500 and possibly 

 even 6,000 feet. The nearly horizontal Cenozoic strata are now 

 found in places at an elevation of 3,000 feet, having been 

 depressed 1,500 feet during the time of Pleistocene glaciation. 

 The high condition of New Zealand at this time united into a 

 greater New Zealand all of the present outlying islands of the 

 New Zealand plateau, no part of which is now submerged 

 more than 3,000 feet. It should be added that Captain Hutton 

 and Professor Dana thought that New Zealand was united with 

 Wilkes Land of Antarctica in late Permian time. 



Historical geology of Australia (see figs. 2 and 3). — In 

 Australia there is no evidence of the Tasman sea during Cam- 

 brian time, for the marine invasions at first were from the 

 south and later across the entire medial portion of the con- 



3 Jas. Park, Geology of New Zealand, 1910. 



