GEOLOGY OF ARCTIC AMERICA 67 



The fossils obtained from these beds are marine and include am- 

 monites and an ichthyosaurus. It would be of great paleontological 

 interest if land deposits with dinosaur remains should be found, 

 connecting the Mesozoic land reptiles of Europe with those of Alberta 

 in America. 



Cretaceous 



Cretaceous beds in the Disko region of western Greenland are 

 of terrestrial origin and furnish a group of land plants suggesting 

 warm-temperate conditions in latitudes from 70° to 72°. There are 

 among them genera that include some species which are now tropical 

 or subtropical, such as ferns related to Gleichenia, cypresses, magnolias, 

 and even leaves suggesting the breadfruit. The plane tree was very 

 common. The contrast with the present Arctic flora with its low- 

 growing herbs and trailing shrubs is a most startling one. 



Seward, in a recent paper on the Cretaceous plant-bearing rocks 

 of western Greenland,^ suggests that the assemblage of plants indi- 

 cates a climate like that of southern Europe, and represents Green- 

 land as the region where angiosperms originated. He gives a map 

 showing how they probably migrated to other parts of the northern 

 hemisphere. 



There are bewildering problems connected with these rich forests 

 of a warm climate several degrees within the Arctic Circle where 

 polar night prevails for weeks in the winter. The necessary warmth 

 might be provided, perhaps, by a suitably arranged warm current, 

 an enlarged Gulf Stream, impinging on the West Greenland coast, 

 but the winter darkness would imply a very untropical cessation of 

 plant growth for a considerable period every year, perhaps the start- 

 ing point for the habit acquired by deciduous trees in temperate re- 

 gions of dropping their leaves in the autumn. 



How doubtful many points are in Arctic geology is well shown by 

 the fact that a good paleobotanist like Seward transfers the West 

 Greenland trees to the Cretaceous, though Heer, who first described 

 them and who has been followed in most textbooks of geology, made 

 them Miocene. ^° In the light of Seward's determinations it seems 

 doubtful whether any Tertiary formations occur in our Arctic sector; 

 and probably the so-called Tertiary coal or lignite of Greenland, Elles- 

 mere Island, and Baffin Island is really of Cretaceous age like the 

 coal of Alaska and Alberta. Until more detailed work has been done 



'A. C. Seward: The Cretaceous Plant-Bearing Rocks of Western Greenland, Philos. Trans. 

 Royal Soc. of London, Ser. B, Vol. 215, 1926, pp. 57-175. 



1° Oswald Heer: Om de miocena vaxter som den svenska expeditionen 1870 hemfort fran Gron- 

 land, dfversigt af K. Svenska Vetenskaps.-Akad. Fork., Vol. 30, 1873, No. 10, pp. 5-12; idem: Nachtrage 

 zur miocanen Flora Gronlands, enthaltend die von der Schwedischen Expedition im Sommer 1870 

 gesammelten Pflanzen, K. Svenska V etenskaps.-Akad. Handl., Vol. 13, No. 2, 1874, also in his "Flora 

 fossilis arctica," Vol. 3, Part 3, Zurich, 1874. See also that work, Vols. 6 and 7, 18S2-1883, and Med- 

 delelser om Gronland, Vol. 5 and Suppl., Copenhagen, 1883. 



