Vol. 54.] GEOLOGY OE PRANZ JOSEF LAND. 635 



immediately in contact with the underlying Jurassic strata is 

 no evidence of its age ; and the presence of a piece of Ammonites 

 Lamberti in the lower part of the basalt may be easily accounted for 

 on the supposition that it was picked up by the basalt as it flowed 

 over Oxfordian beds, or it might have been thrown out with the 

 lava. 



Much stronger evidence, however, is that of the plant-bed, which 

 has been found at two or three localities between the second and 

 third tiers of basalt, and in one case, although little more than 

 18 inches thick, could be traced continuously for 600 yards, and 

 had a thick bed of coarse tuff underlying it. The rock of this bed 

 has all the appearance of a line tuff, but seems not to be of this 

 nature (see p. 634). The plant-remains from one of these beds 

 were examined by Dr. Nathorst, who believes them to be of 

 Upper Jurassic age.^ 



The foregoing facts lead me to believe that the lower, at least, 

 of the basalts of this part of Franz Josef Land are of Upper Jurassic 

 age ; and although I am aware that the opinions of those who have 

 studied the basaltic formations elsewhere lean strongly in favour 

 of all these lava-sheets being of Tertiary age, yet, judging from 

 what I saw during my sojourn in Franz Josef Land, I believe 

 some of the basalts of the southern parts of that country to be of 

 the same age as the plant-beds associated with them ; and if these 

 be of Upper Jurassic age, then most of the basalts are so likewise. 



The basaltic rocks, for the most part, are found at the higher 

 levels and form the plateaux of most of the higher capes. But at 

 certain places these rocks descend to the sea-level ; this is the case 

 at three localities on IS'orthbrook Island, namely, Barents Hook, 

 the head of Giinther Bay, and at Camp Point. In all three places 

 the rock is of a compact character. 



At three localities on Hooker Island the basalt is found at the 

 sea-level ; and north of Dundee Point a basaltic mass some 300 or 

 400 yards in diameter rises from the sea to a height of 300 or 400 

 feet. There is no talus around this rock, and the summit seems to 

 form a basin ; I was unable to approach very closely, but this mass 

 has all the appearance of the core of a denuded volcanic vent. 



In the upper part of the Jurassic rocks at the back ofElmwood 

 there is what I at first thought was an intrusive sill. This consists 

 of a layer of vesicular basalt, 6 feet thick, which rests upon clay- 

 stone and has 3 feet of similar claystone above it ; following this 

 is 40 to 50 feet of coarse tuff, succeeded above by the main mass of 

 the basaltic cliff. The vesicular character of this ^ sill ' leads me to 

 suspect that it may be an old contemporaneous lava-flow. 



At Cape Crowther massive columnar rock rises, at one place, 

 from the sea-level to a height of perhaps 100 feet. The top of this 

 is a more or less level surface, apparently a raised beach, extending 



^ See p» 648, and also this Journal, vol. Uii (1897) p. 495. 



2t2 



