L06 K. Suess — Paleogeography of North America. 



all over the world in the undisturbed regions except parts of 

 the Sahara. 



I will try to point out but two peculiarities of the upper 

 Cretaceous transgression : 



a. The great inundation does not, as far as I know, attain 

 the northernmost coasts and islands of Eurasia. Here, on the 

 contrary, transgressions appear in undisturbed (only faulted) 

 regions, a condition which we are not accustomed to see in 

 these areas. Such are the upper Carboniferous and Triassic 

 marine beds of Bear Island, etc. ; the Kelloway, etc., which has 

 been described ; then Lias at one locality in northeastern Sibe- 

 ria; the Volga beds of lower Cretaceous age in northern Rus- 

 sia ; the coast of Siberia, also spreading to the center of Russia; 

 and finally the circumpolar late Cham plain transgression. It 

 seems almost as if in certain Mesozoic phases the transgres- 

 sions in undisturbed regions were complementary to those in 

 lower latitudes. The upper Cretaceous inundation is traceable 

 to Scotland, attains Scania and Moscow, but is not known far- 

 ther in the north. Angara land (eastern Siberia) and China 

 have as yet not given a sign of this transgression. You 

 know by far better than I that North America shows the con- 

 trary. The upper Cretaceous transgression clearly extends to 

 Yesso and Sakhalin, in northern Alaska along the, arctic 

 coasts about Colville River to the delta of the Mackenzie 

 and thence southward into the United States. The undis- 

 turbed arctic and subarctic coasts therefore show quite a differ- 

 ent marine series in Eurasia and in America. 



i. The wide inundation of so many continents and the 

 succeeding probably rather rapid retreat of the marine waters 

 also dissipated the land waters, resulting in the destruction of 

 the large dinosaurs, the inhabitants of swamps, rivers and 

 lowlands, and retaining only those types of Reptilia which 

 exist unto the present day. The freshwater fauna was driven 

 into the upper reaches of the rivers. The Pyrgulifera from 

 Bear River have a very remarkable affinity with the forms 

 from the upper Cretaceous beds of the Gosau of Hungary and 

 similar forms from southern France. The Pyrgulifera living 

 in Tanganyika lake resemble them so much that I am willing 

 to believe that this African freshwater fauna is not a relict 

 of the Cretaceous transgression which seems not to have 

 attained to that jrart of Africa, but the descendants of the 

 habitants of higher parts of an uj)per Cretaceous river from 

 the time of the transgression, exactly as Baikal preserves some 

 species of Levantine age. 



I will dwell a little longer on the most important question of 

 fluviatile faunae about which more is said in the last chapter of 

 my book. The development of lungs preceded by gills teaches 



