443 
Geology of the Environs of Petersburg . 
traces of one. The branch stretching to Shulcova, and the detached 
ridge opposite its termination, possess the same characters, and are 
almost inaccessibly steep. The rock appears every where through 
the soil, and in the latter instance there is reason to believe it is 
highly inclined,* though no good section can be obtained. These 
detached summits, Cargasary, Teply Sad, Doudorof, and Shulcova, 
all possess a similarity of character sufficiently striking even at first 
sight. 
The ravines of Great and Little Coirova, especially that which 
runs through the dell in the old Solticof garden, also the lower part 
of the Coirovca and neighbouring streams, should be visited for 
good sections of the blue clay, and in the localities mentioned in 
their proper place, for examples of the clay veins. 
All the streams along the eastern escarpment merit particular at- 
tention : the Pulcovca, Couzminca, Goumolosarka, * Coshelevka, 
Popovca, Slavenca, Ishora, and Tosna, should each be followed up 
from the places where each respectively quits the escarpment to 
where they rise to the level of the land around them. The Pulcov- 
ca, as exhibiting certain remarkable phenomena connected with 
an outlier of the limestone, I shall leave to be more particularly 
described at the end. The Couzminca is remarkable for the total 
absence of any thing but blue clay in its banks, since it flows within 
* A disposition of this rock to separate into cubic fragments has already been noticed. 
In this instance, the western escarpment shews the rock peeping through the soil ; no stra- 
tification is visible as in the case of the precipices at Doudorof and similar situations, but 
what appears to be the back of the beds is seen with its remarkable cross fracture dividing 
it like a network of irregular veins. The slope of the back of these beds, if I am correct 
in terming them such, coincides with that of the hill itself. 
* The Russian name for the rivulet which waters the village of Houmolosarry. This 
name is Finnish, but the Russian alphabet being unable to express the sound of the letter 
H as the natives are to pronounce it, they have prefixed their usual guttural, which is un- 
known to the Finnish language, and added the common Russian termination. 
