168 
GEOLOGY. 
Avatscha. The same rock is seen forming the foot of that part of the low range of 
hills behind Petropaulski, where they border the lake on the eastern side. Veins of 
variously-coloured quartz, assuming the character of jasper and chert, and of finely 
waved talc-slate, lie between the strata. 
The cliff, that first forms the sea-shore beyond the lake, in going to Avatscha, is 
less distinctly stratified, but where it can be perceived to be so, the direction and dip 
are nearly the same as in the isthmus already mentioned. The clay-slate is replaced 
by talc-slate and basaltic porphyry, whilst the quartz rocks continue the same. A basal- 
tic tufa and green-stone, passing into serpentine, also prevail. Farther on, and close 
to Avatscha, the cliffs are more generally formed of green-stone passing into serpentine. 
From this part round the head of the bay to Paratunka the shore is low, and the 
country plain for a considerable way to the foot of the snowy mountains, which form the 
interior of Kamschatka, and assuming the form of an amphitheatre, terminate the view. 
Several small and shallow creeks are formed in this low ground near the sea, and 
are remarkable by the raised banks, so similar to an artificial embankment as to have 
suggested the idea to some of their having been constructed by art. To me these 
mounds or dykes appeared the produce of the natural operation of the waters which 
they contain. 
Coming out of the bay, I observed a vein of several feet thick, composed of hori- 
zontal basaltic columns, in the cliff forming the western side of the entrance. 
bj)ecime7is. 
No. 1. Clay-slate, forming the general rock of the coast from Petropaulski to the 
entrance of Rakowena harbour. 
No. 2. Greenish quartz and jasper, in No. 1. 
No. 3. Horizontal strata of slate-clay hardened, under No. 4. 
No. 4. Columnar porous basalt, forming the second promontory on the right side of the 
harbour of Rakowena. 
No. 5. Trap tufa, forming part of the cliffs in Rakowena harbour. 
No. 6. Small-grained greenish trap tufa, forming part of the same cliffs as No. 5. 
No. 7. Rolled basalt, forming part of the tufaceous cliff on the right side of the en- 
trance of Rakowena harbour. 
No. 8. Quartz, serpentine and asbestos, imbedded in cliff No. 7. 
No. 9. Chalcedony, in veins of cliffs, in Rakowena harbour. 
No. 10, Chalcedony and crystals of greyish felspar in green-stone porphyry, in the 
right hand cliffs of Rakowena harbour. 
No. 11. Brownish jasper (altered by heat), from the cliffs of Rakowena harbour. 
No. 12. Brownish felspar porphyry, with crystals of felspar, forming large beach stones 
in Rakowena harbour. 
No. 13. Reddish felspar porphyry, occurring with No. 12. 
No. 14. Porphyritic green-stone, from the cliffs of Rakowena harbour. 
No. 15. The same as No. 14, enclosing basaltic hornblende; locality of No. 14. 
No. 16. The same as No. 15, lighter coloured ; same locality. 
