382 



THE GEOLOGIST. 



4. " On the Probable Events which succeeded the Close of the Cretaceous 

 Period." By S. Y. Wood, jun., Esq. Communicated by S. V. Wood, Esq., 

 E.G.S. 



The object of this paper was to show that the close of the Secondary period 

 was followed by the formation of a continent having a great extent from east 

 to west, and at that time chiefly occupying low latitudes ; that this direction 

 of continent prevailed throughout the Tertiary period ; and that in certain por- 

 tions of the southern hemisphere, particularly in Australia and New Zealand, 

 there have been preserved portions of the Secondary continent with isolated 

 remnants of the Secondary mammalia and gigantic birds. These conclusions 

 were atrived at by a consideration of the direction of the principal volcanic 

 axes in the Secondary and Tertiary periods. The Secondary continent was 

 (the autlior considered) mainly influenced in the northern hemisphere by vol- 

 canic axes which came into action at the close of the Carboniferous, and 

 continued through the Secondary Period. These axes were that of the 

 Oural, that of the north of England prolonged into Portugal, and that of the 

 Alleghanies, having all a north and south direction, supervening upon volcanic 

 axes having a direction at right angles to them, which had prevailed during the 

 Newer Palgeozoic period. Erom this circumstance an inference was drawn 

 that the Secondary continents had generally a trend from north to south, 

 governed by volcanic bands having this direction; while, as the Secondary 

 formations indicate a great extent of sea over the northern hemisphere, the 

 balk of the Secondary continent lay in the southern hemisphere. 



The elevation of the bed of the Cretaceous sea, it was inferred, was due to 

 volcanic forces acting from east to west ; and the author adduced evidence of 

 this action having become perceptible during the later part of the Cretaceous 

 period. He considered that the direction of all the Post-cretaceous lines of 

 volcanic action governed the direction of the continent during the Post- 

 cretaceous period, and pointed out that these were all in an easterly and 

 westerly direction, coincident with the existing volcanic band which extends 

 from the Azores to the Caspian, and thence (with an interval of intense earth- 

 quake action between the Caspian and Bengal) extends to the Society Isles. 

 He concluded that tliey gave rise to a continent extending from the Carribbean 

 Sea to the Society Isles — many reasons uniting to show a land-connexion be- 

 tween America and Europe at the dawn of the Tertiary period, the submerged 

 continent of Oceanica also indicating the easterly extension of Southern Asia ; 

 and that, since this continent receded to the nortli at the dawn of the Tertiary 

 period before the inroad of the Nummulitic Sea (which stretched from the 

 south-east through Western Asia and Southern Europe, and was, as the author 

 conceives, the oceanic equivalent of the Eocene basins of Europe) the greater 

 portion of the deposits formed in the interval between Cretaceous and Eocene 

 times must be now under the Southern Oceans. 



The author then adverted to the circumstance that the recent great \\Tngless 

 birds and the nearest living affinities of all the Secondary mammalia yet known 

 occur only in the southern hemisphere. Erom this, and from some considera- 

 tions as to the vegetation, he concluded that, while parts of the Secondary con- 

 tinent yet remain in that hemisphere incorporated more or less into the Post- 

 cretaceous continent, otlier parts of it, such as Australia and New Zealand, 

 have remained isolated up to the presem time to an extent sufficient to pre- 

 chidc the migration of mammalia and wingless birds. He inferred that the 

 whigloss birds, excepting the swift Strutliionidoe, have been preserved solely 

 by isolation from the carnivora, which do not appear as an important family 

 \mlil llic Pliocene age; and he instanced the Gastrornis of the Eocene (which 

 li;ul alliuiiics with tlie Solitaire and Notornis) as evidence that the apterous 

 birtls had survived until that period. 



