CENOZOTC TIME — TERTIARY. 937 



the fact of the great continental elevations of the same time. The Coral 

 Island subsidence, announced by Darwin in 1839, recognized such geosynclines ; 

 and they were long since set forth by Dana as the counterpart of the conti- 

 nental movements. The subsidence is thus a real event in geological history ; 

 and if marvelous, equally so is that of the world's so recent elevations. 



'' Gondwana-Land," connecting India with southern Africa (page 737), 

 continued to exist, according to Oldham (1894), from the Carboniferous 

 period throughout Mesozoic time, and " sank beneath the sea in the Tertiary 

 era," leaving some volcanic and coral islands in its course, including to the 

 northward the sunken atoll of the Chagos bank. The extension of '' Gond- 

 wana-Land" over the Indian Ocean is not here in view, because it is not 

 believed to have ever been a fact. 



A paper by Haddon, Sollas, and Cole {R. Irish Acad., 1894), after men- 

 tioning the observation of Jukes that the eastern mountain range of Aus- 

 tralia, extending for 35° of latitude from Tasmania to the northern cape, 

 Cape York, is continued in islands across Torres Strait to New Guinea, and 

 describing the straits and the lands beyond, concludes that this southern 

 continent lost its border lands of New Zealand, New Caledonia, and New 

 Guinea and the intermediate islands "possibly during the great Alpine and 

 Himalayan revolutions " of the Tertiary period. 



Igneous eruptions during the Tertiary. — An eruptive period in the 

 earth's history commenced in the Later Cretaceous (page 875) and passed 

 its maximum in the course of the Miocene. Eruptions through fissures cov- 

 ered vast areas of the Pacific slope with igneous rocks, and volcanic erup- 

 tions made great volcanic cones, which added largely to the outflows and 

 ejections. The eruptions continued through the Pliocene, and some of the 

 cones are not yet extinct. The loftiest of the volcanoes are situated along 

 the Coast region, from Washington to northern California, the heights vary- 

 ing from 10,400 to 14,500; and those farther south along a belt through 

 Mexico — the highest three, Orizaba 18,200 feet, Popocatapetl 17,500 feet, 

 and Ixtaccituatl 16,770 — are probably of like Miocene origin. 



Some of the regions of fissure eruptions have been already described. 

 South of Lassen's Peak, in northern California, the southernmost of the 

 cones of the Pacific border, the region of the Sierra Nevada had its outflows 

 of broad streams of basalt from fissures which were later cut up into Table 

 Mountains ; and similar floods occurred over Nevada, New Mexico, and 

 Arizona. 



The higher western slopes and summit region of the Rocky Mountains 

 also had their cones. The Yellowstone National Park and its vicinity was 

 one of the volcanic centers. Electric Peak and Sepulchre Mountain are two 

 denuded cones in the Park, as described by Iddings ; Emigrant Peak, on the 

 Yellowstone, 16 miles north of the boundary, is another, where dacyte and 

 quartzose porphyry are the igneous rocks ; Haystack Mountain, 12 miles 

 north of the east corner of the Park, is another, its cone consisting of gabbro 

 and dioryte ; and another stands just east of the east corner of the Park, 



