EVIDENCES OF VOLCANIC ACTION 11 
and Lindström gives a bulk analysis of a diabase-aphanite with 
6.85 2/0 alcalies from Konyam bay.! Neither their age nor their 
geological position is made mention of. Mesozoic sediments, even 
in remnants, seem to be wanting there; the broad north going 
valleys and the flat topped rising ground between the different 
fiver systems seem to be an old and largely dissected peneplain 
with far driven maturity. Raised river beaches or old shore lines 
marked by basalt flows seem to be wanting. A preliminary revision 
of the rocks brought home by the 1909 coast survey expedition 
(Tolmachoff) could not discover any representative of this late group 
of volcanics. Even from Wrangel Land only older sedimentary rocks 
(probably of palaeozoic age) are brought home. ? | 
The first clear evidences are from the Bennett Island group, in- 
cluding here the small islands in the southeast, as Jeanette and 
Henriette, and those more advanced to the east, discovered by Wil- 
kitski during the coast survey of 1915. The smaller ones of this 
group seem to consist entirely of basaltic volcanics and rise from 
the ocean level as steepsided cliffs. The geological structure of 
Bennett Island is a more variegated one, as shown by the deceased 
Baron Toll in his last report brought home with his collections two 
years after his tragic dead (1902). The oldest rock is a black grap- 
tolite slate of cambrian age in undisturbed horizontal position, expo- 
sed only in the deeper cuts of the island. Upon this floor, with 
great stratigraphical diastrophism, there rest marly continental depo- 
sits containing undeterminable fossil plant remains of jurassic age. 
The uppermost part of the sedimentary series is a soft yellowish 
1 G. Lindström, Analyser af bergarter och bottenprof fran Ishafvet, Asiens nord- 
kust och Japan. Stockholm 1884. 
2 On the map accompanying the „Explanatory text to the geological map of the 
part of Siberia investigated by order of the Siberian Railway Comittee“ (St. Peters- 
burg 1906, compiled by L. Jaczevski), there are indicated large areas of „andesite, 
partly basalt, trachyte and liparite“ on the shore and on the inland immediately 
west of Behrings sound; no exact report upon these mixed rocks is known to the 
writer. — On the islands north of the Kolyma-mouth, according to reports of 
Wrangel there is some possibility to meet with young effusive rocks. 
