14 ARCTIC BASALT PLATEAU 
approaches the sea shore between the mouths of the Yana (Ust- 
yansk — Kazachyé) and the Lena (Tiksibay) rivers. From this point 
there are reported! flows (?) of columnar basalt and hot springs con- 
nected with them; no advice upon allied sedimentary rocks is given. 
From the river Lena crossing the Werkhoyansk range near Bulun 
no geological news are reported. The geological position of the 
basalt-(diabase-)sill (?) near Bolkalakh at the mouth of the Olenek 
amidst sediments of mesozoic age belonging to the mentioned 
range, is not further elucidated. Upstreams the river Olenek the 
nearly unbroken basalt plateau joins, extending to the upper Vilui 
river and its affluents on the one side, to the Anabar and Khatanga 
rivers on the other side, connecting with the Tunguska plateau.and, 
passing the upper Piasina river, with the basalt of the Yenisei 
mouth. A reference to the geological individualities of this Siberian 
basalt plateau in a narrower sense will be given in a further chapter. 
From the Alexei Island, between cape Tchelyuskin and the new 
discovered Nicholas Land, there is brought home a numerous col- 
lection of ice drifted pebbles of a typical fine grained diabase (ba- 
salt); the whole island is covered with quaternary deposits. By 
soundings there are drawn up from the sea bottom eastward from 
the island and southward, in the Thaddaeus bay, several pebbles of 
a similar diabase, covered with a manganese core. From the Ni- 
cholas Land the examined phyllitic slates, folded and contorted, 
are a proof of the rugged mountain chain reported from there. 
Greenstone samples brought home from the shore eastward of 
the Piasina mouth and from the islands off side the recently disco- 
vered Minin bay seem to belong, in spite of their basaltic origin, 
to an older formation; they are strongly crushed and metamorphosed. 
On the other hand, the basalt flows of the upper Piasina river, on 
the Noril Lakes, from where they are reported by Schmidt and 
others, belong to the plateau and follow the river valley down at 
1 By the last wintering party (1902/1903) of the Baron Toll expedition. 
