16 ARCTIC BASALT PLATEAU 
east coast on the same latitude. The basalt crowns undisturbed 
sediments of mesozoic age, and seems also to occur as concordant 
dikes in this formation, the last strongly contrasting against the 
palaeozoic folded strata on the west-coast and representing by this 
means some ressemblance to the geological features of West-Spits- 
bergen. The relations of the geological structure of the east- and 
west-coast are not revealed on account of the central covering ice cap. 
Åt last Franz Joseph Land by Suess is referred to the-Petchora 
_plain,! the former being the supposed extreme northern continuation of 
the latter. Already Count Keyserling, during his travels in the Pet- 
chora Land in 1843, encountered glacial drifted boulders containing 
marine fossils of upper jurassic age in the Bolshezemelskaia tundra. 
Later on, the original localities of jurassic rocks were stated on the 
southern shore of the river Petchora near the Ishma confluence. In 
1909 jurassic red clay deposits, containing Cardioceras alternans 
v. Buch and Aucella Bronni Lahus. as characteristic fossils deter- 
mining their age as sequanian, were reported from the river 
Adzva, about 100 kilometres north of the confluence with the river 
Ussa, thus from a locality in the central part of the tundra. Only 
small remnants of these sediments preserved from glacial erosion 
are reported. Immediately in the neighbourhood of these deposits 
several small outcrops of a dissected basalt surface-flow, periectly 
glacial-smoothed, are met with on the river Adzva; the hills are partly 
covered with glacial deposits, but the geological relations of the basalt 
to the older sediments developed on the river, vic. to the carboniferous 
southward (Productus-limestone), to the permo-carboniferous (sandstone 
with plant remains) and, as mentioned before, to the upper jurassic 
clay in the nearest vicinity are not closely examined, unless they cut 
the former two formations. However, fragments of a sedimentary rock 
having great ressemblance to the jurassic clay and enclosed in the 
Saye EE HT ICH CT , 
1 E. Suess, I. c. p. 945: ,— — — ces iles affectent une structure tabulaire; 
elles sont situées entre les branches des Ouralides, et il est permis de considerer 
le plateau comme un prolongement de la plaine de Petchora — — —“. 
