CORRELATION. 



149 



The followinp; Wilcox species are found in tlio 

 Fort Union: Glijptotitrohufs europseus, Taxodiurn 

 duhium, Hicoria antiquoruvi , Juglans schim.peri, 

 Ficufi artocarponJfs, Farrotia cuneata, Legumino- 

 sites aracliioides, Cdastru^ taunnensis, Ter- 

 minalia Jiilgardiana, Aralia acerifoUa, Aralia 

 notata, and Dwspyros hracliysepala. Seven of 

 these species arc not found in the Raton or 

 Denver formations, so that there are alto- 

 gether 41 Wilcox species, or more than 10 per 

 cent of the flora and about half of the Wilcox 

 species that have an outside distribution, which 

 occur in the Raton, Denver, or Fort Union 

 formations of the western interior region. 

 Wilcox species which have closely related forms 

 in the P^ort Union are Ficus monodon, Ficits 

 pseudopupulus, C'innamom.um ndssisnippiensis, 

 Cinnamomum hucJiii, Oreodapitne cousiuittu, 

 CelaMrus veatclii, Euonijmus f;plendens, Sajiin- 

 dus pseudaffinis, Sapindus oxford ensis, Sapindus 

 ■formosus, Sapindus eoligniticu.^, Rhamnus eolig- 

 niticuft, Greiviopsis tennesseensis, and Apocyno- 

 phyllum sapindifoJium . 



Aftt^r eliminating duphcations there are in 

 addition '21 Wilcox species which have ch)scly 

 related forms in the Raton, Denver, or Fort 

 Union formations. The Fort Union embraces 

 a great thickness of continental deposits wliich 

 extend from the top of the Lance formation 

 upward to the base of the Wasatch, so that it 

 obviously extends from a horizon near the base 

 of the Eocene to the Wasatch, which is corre- 

 lated by Osborn ' with the Ypresian of France. 

 It therefore follows that the WUcox is in jiart 

 the equivalent of the Fort Union and the 

 Wasatch. It might have been expected that 

 there would be much more comniunity of 

 facies between two such extensive floras of so 

 similar age, but this is not the case. The Fort 

 Union flora abounds in hardwood trees of up- 

 land type and temperate afHjiitics. It grew in 

 a topographically varied region of wide extent 

 and great inequalities of climate, especially of 

 rainfall, remote from the sea, and it appears to 

 represent, in part at least, a southward spread- 

 ing of more northern forms. 



FLOE.\ OF THE GREENLAND TERTIARY. 



More than 200 species of Tertiary plants 

 were recorded by Heer from western Green- 

 land. This very remarkable flora was de- 

 scribed from material niore fragmentary than 

 Heer's figures would lead one to suspect. 



' Osbom, H. F., U. S. GeoL Survey BuU. 361, 1909. 



I leer's preparation for this great work was liis 

 long-continued studies of the Swiss Miocene 

 (Acjuitanian to Tortonian), so that many of 

 the Greenland fragments naturally received 

 names of the European Miocene forms most 

 familiar to their describer. Many of these 

 dctciininations of Arctic plants are erroneous, 

 and until the subject is reworked with the 

 original material at hand attempted correla- 

 tions are fruitless. Heer called the Greenland 

 flora Miocene. Saporta, and following him 

 Starkie Gardner, pointed out its earlier age. 

 It is referred to the Eocene in the last edition 

 of De Lapparent, and Menzel recently advances 

 the view that it is in pavt Eocene and in part 

 Acpiitanian. Students in general have come 

 to assume that it was Eocene or Oligocene, the 

 preponderance of opinion perhaps favoring its 

 Eocene age. 



The following 5 Wilcox species occur in the 

 Greenland Tertiary: Glyptontrobus europieus, 

 Taxodiurn duhium, Aralia jorgenseni, Fraxinus 

 johnstrupi, and Echitonium lanceolatum. Two 

 or tliree additional Wilcox species are repre- 

 sented in Greenland bj" closely allied forms. I 

 consider the Wilcox as older than the Green- 

 land Tertiary, the interval being perhaps 

 measurable by the time it took these forms to 

 reach Greenland from the embayment region. 

 In the embayment region the succeeding 

 Claiborne floras are more tropical than the 

 WQcox and those of the Vicksburg group (lower 

 Oligocene) mark the maximum of the north- 

 ward trend of equatorial conditions. The 

 Greenland Tertiary flora was possibly contem- 

 poraneous with these southern floras, from the 

 Claiborne to the Vicksburg, wliich show the 

 most tropical conditions. It would not be 

 worth whUe to dwell on this point were it not 

 that in the Upper Cretaceous the floras of the 

 embayment can be traced without any striking 

 change from Texas and Alabama northward in 

 the interior and along the Atlantic coast to the 

 same localities in western Greenland. The 

 difference in this respect between the Upper 

 Cretaceous and Tertiary is still unexplainable. 



KELATION TO ETJKOPEAN EOCENE FLORAS. 



Though it is not yet possible to make exact 

 correlations of minor horizons on the two sides 

 of the Atlantic the increasingly apparent syn- 

 chroneity of the more im])ortant diastrophic 

 events lends support to tlie thcoiy that tii(>se 

 events are (kie to sjencnd and not local factors. 



