GEOLOGICAL AGE OF THE PLANT-BEARING DEPOSIT. 



A glance at the accompanying list (on pp. 23 24) of the fossil plants 

 described in these pages, will at once prove to specialists that the fossil flora 

 from the deposit between the basalt beds of Franz Josef Land, has its greatest 

 resemblance with the previously known Jurassic floras from Siberia and Spits- 

 bergen. Of these, that of Siberia and the flora of Cape Boheman of Spitsbergen 

 have by Heer (and afterwards by me) been brought under the Brown Jura, an 

 opinion which, as regards the latter flora, is no longer tenable ; the investigations 

 carried on by me during the summer of 1898 having proved that it must be 

 placed above the Oxfordian Aucella-bearing deposits. We may thus, to begin 

 with, affirm that the plant-bearing deposit of Franz Josef Land is younger 

 than the Oxfordian, or belongs to its uppermost portion, which also harmo- 

 nises with the supposition of the lowest basalt-bed having its place above the 

 Oxfordian marine deposits containing Ammonites Lamberti. There is, 

 moreover, no doubt whatever that the flora of Franz Josef Land is younger 

 than that of Cape Boheman and Siberia, a circumstance which is proved by 

 its ample supply of the Pinites species. In this respect it agrees more with 

 the youngest Jurassic flora of Spitsbergen, viz: that described by me as found 

 at Advent Bay, and by Heer as discovered at Cape Staratschin. As a mat- 

 ter of fact the most common species found at Franz Josef Land seems iden- 

 tical with Pityophyllum IAndstr0mi Nath. also so common in the deposit 

 at Advent Bay. The age of this deposit I have tried to define by stating 

 that "the nearest approach to truth is made by counting the deposit as Upper- 

 most Jurassic, to a horizon which is somewhat older than the Wealden." 



The agreement between the fossil flora of Franz Josef Land and Advent Bay 

 is, however, far from complete. Most remarkable is the absence, at Franz Josef 



