Geology of the Environs of Petersburg . 
417 
central parts of England : for instance, on the banks of the Teme, 
in Worcestershire, to which this part of the Ishora bears some 
resemblance. Again it is seen with the same characters near the 
entrance of a considerable ravine or hollow in the Shoundorovsky 
escarpment, where the road from Gorela to Ropsha crosses a brook 
near the village of Niccozy ; it is here slightly micaceous, and 
offers to the attention of the botanist the beautiful Epilobium 
hirsutum, the only spot where that plant is found near Petersburg. 
Towards Ropsha the outcrop is covered up (as are most of the 
eastern slopes of the vallies of denudation) by a thick bed of 
granitic gravel. The hill of Khamouzy, and the heights near it, 
are so covered with gravel and soil, that their composition cannot 
be exactly ascertained. 
The Pleta Limestone 
Covers the intermediate bed last described. .It is a coarse limestone, 
the lower beds of which are very argillaceous, and contain a large 
portion of green earth : they are, in fact, only harder beds of the 
same substance as that which forms the upper part of the 
intermediate bed. The most common colour of this limestone is a 
yellowish grey, sometimes spotted or variegated with green, red, 
dull purple, and bright yellow, or even orange of different shades. 
The great mass of the limestone also contains much clay, which 
seems to have been favorable to the preservation of the organic 
remains contained in it ; but the upper beds are considerably harder 
and more sandy, and contain much fewer traces of a former world. 
As there is no one section which gives so distinct a view of its 
beds and their peculiarities, as the cliffs of the Ishora do of those 
forming the intermediate bed, I must describe them in their order* 
referring to localities where they may be examined and identified. 
3 g 2 
