G. R. Wieland — Polar Climate in Time. 419 



l^ordenskiold and Steeiistrup, and studied by Professor Oswald 

 Heer, the cliief results being published in his magnificent 

 monograph the Flora Fossilis Arctica. 



Heer divided the Greenland beds into (1) the Kome lyeds^ (2) 

 the Atane heds, (3) the Patoot heds and (4) the Tertiary leds. 

 In all there occur more than 600 species of plants. 



In the lower or Kome heds (the so-called Greenland Urgonian), 

 twenty or more Cycads, as many Conifers, a number of ferns, 

 five Monocotyls, and one Dicotyl are present. The Cycads are 

 mainly of a quite modern type and also include a species close 

 to Cycas revohota^ now native of warmer Japan, but are almost 

 uniformly dw^arfisli forms. The conifers, sequoias, and pines 

 seem to have formed extensive forests. The single Dicotyl 

 {Poj)ulas primaeva) was regarded as the oldest of all the 

 dicotyls until the later discovery of primitive dicotyledonous 

 types in the lower Cretaceous of Maryland and Portugal, to be 

 again mentioned. Heer concluded that the mean temperature 

 when the Kome beds were laid down was about 71° to 72°. 

 This is that of Cuba now.* 



In number (2) the Atane heds there occur at Lower Atani- 

 kerdluk more than fifty Dicotyls, including the fig and the 

 bay. There are fewer ferns and a diminishing number of 

 conifers, and the presence in this much changed floral facies of 

 about four C^^cads shows them to be a waning group, although 

 no other than very slight decline in temperature is indicated. 

 In {Z) i\\Q Patoot heds the Dicotyls reach a fully established 

 sway, numbering about 70 species with 18 conifers, whilst the 

 Cycads disappear. Oaks and planes are here the most abun- 

 dant forest trees, and alders, maples, figs, bay, walnuts and 

 birches are present. A secular decline in temperature is 

 indicated. In all these florge a noteworthy phenomenon often 

 noted amongst Upper Cretaceous plants and eloquent of the 

 origin of the Dicotyls in a moist and hot climate, is the growth 

 side by side of forms whose nearest i^elatives are now found 

 quite exclusively in either temperate, warm temperate or hot 

 climates. Thus in the Atane beds the bread fruit tree, now 

 only found in the hotter lands, grew side by side with the oak 

 and chestnut. 



The Greenland Tertiary includes twenty beds containing 



* A quite similar climate and forest facies is indicated by tlie fossils of the 

 "Lower Cretaceous" cycad-bearing horizons of the Black Hills "rim," where 

 large numbers of cycads, possibly in part of a somewhat older general type 

 than those of the Kome beds, formed the underbrush or grew in the open dells 

 of great coniferous (Araucarian) forests. The beautifully silicified trunks 

 with the leaves and fruits of the Bennettitalean cycads and numerous 

 immen'se Araucarian silicified logs as well as many plant impressions tell the 

 story. It is significant that here as elsewhere the sway of the gymnosperms 

 was very suddenly disputed by the inrush of Angiosperms, with but very 

 few precursor forms. 



