THE MAGNOLIA AND TULIP-TREE 179 



and Wyoming, and the second the remarkable Liriodendron alatiim 

 (fig. 4) with its winged leaf-stalks, which is found in Colorado and 

 Utah. 



Cretaceous times were brought to a close by widespread land 

 emergence and this emergent condition prevailed for a very long 

 period of time, in fact at no subsequent stage of the earth's history 

 was there anything approaching the degree of submergence attained 

 during the Cretaceous. Finally there was a period of renewed 

 submergence which ushered in the Tertiary. This early Tertiary 

 renewal of sea expansion resulted in such a disposition of the land 

 and water that extensive mediterranean seas had free connections 

 with the Arctic not only from the Atlantic and Pacific oceans, but 

 also across Asia, and this resulted in mild and comparatively uni- 

 form chmates. The fossil floras of that time show a poleward 

 expansion of the equatorial floras of that time, so that in south- 

 eastern North America we find few temperate types and no tulip- 

 trees. They are found, however, in British Columbia, Greenland, 

 Iceland, and England during the later Eocene. The Oligocene 

 records which follow those of the Eocene have furnished no repre- 

 sentatives of the tulip-tree, but well marked Miocene forms, repre- 

 senting two or three species are found in Italy, Switzerland, and 

 Bohemia. None have been discovered in the Miocene or Pliocene 

 floras of North America, but neither of these, and especially that 

 of the Pliocene is at all well known. 



There were at least three species still surviving in Europe during 

 Phocene time and immediately preceding the Glacial period (figs. 

 6, 7). These were found in Italy, France and Holland, and their 

 remains comprise both leaves and characteristic fruits in the last 

 two areas. Those from Holland cannot be distinguished from the 

 still existing American tulip-tree, which adds another item to the 

 long array of facts which show that the similarities in the existing 

 floras of North America and eastern Asia and the dissimilarities 

 shown with the flora of Europe, are due very largely to the havoc 

 wrought on the last continent by the intense glaciations combined 

 with the peculiar geography and topography of transverse moun- 

 tain chains and mediterranean seas which largely prevented the 



