726 
streams and currents that flowed from the adjacent Ural moun- 
tains, which, it will be shown, were, during very early periods, the 
site of great copper veins *. vi 
As a solution of copper which was let loose by accident in modern 
times upon an adjacent peat bog in North Wales specially affected 
and impregnated the vegetable fibre in preference to the accom- 
panying soil, so is it conceived that the forests washed into the sea 
in which the Permian deposits were accumulated, attracted around 
them the cupriferous matter contained in the transporting currents. - 
This point will be reverted to in the subsequent sketch of the Ural 
mountains. 
The general succession of these Permian deposits is then described 
on several parallels of latitude between the Ural and the Volga, and 
also their outliers in the steppe between Orenburg and Sarepta ; 
and it is shown, that this vastly extended and diversified system, 
containing not only copper deposits but also large masses of gyp- 
sum, rock-salt and copious salt-springs, lies in an enormous trough 
bounded on the north and east, and south-west, by the carbonife- 
rous limestone on which it reposes. 
By their examination during the past year, the authors have 
cleared away some difficulties which obscured their former views. 
By reference to the abstract of their first memoir (anté, p. 402), it 
will be seen, that they considered (though with much hesitation) 
certain limestones and beds of gypsum which occupy cliffs upon the 
Dwina to the south of Archangel, and extend to Pinega and to- 
wards Ust Vaga, to be upper members of the carboniferous lime- 
stone. By a comparison of the Productz and other fossils, and 
the great masses’ of gypsum which they contain, these northern 
beds are’now brought into direct identification with the true Per- 
mian or Zechstein deposits. In the south-western termination 
of this vast basin near Samara, the Permian rocks, particularly 
at Usolie, rest in patches of a dolomitic conglomerate upon the 
steep escarpments of the carboniferous limestone, out of the mate- 
rials of which they have been formed, and do not present that 
regular succession which they exhibit when followed westwards 
from the slopes of the Ural chain. It is also observed, that though 
gently undulating or horizontal over all the lower regions, these 
rocks, on approaching the Ural mountains, are occasionally thrown 
into anticlinal axes of some length, parallel to the direction of the 
palzeozoic rocks of the adjacent chain. 
In a sketch of the outliers in the Steppe of the Kirghiss, the base 
* Among the mineral analogies between the Permian rocks and those of 
the magnesian limestone it appears, from Professor Sedgwick’s description 
of the latter, that traces of lead ore and also of copper, are found in it in 
small quantities, which that author considers to have been derived from the 
large mineral masses of the same in the surrounding and more ancient car- 
boniferous limestones, Lead is also worked in the dolomitie conglomerate 
of the Mendip Hills, where it is associated with calamine. See memoir of 
Mr. Conybeare and Dr. Buckland, Geol, Trans., 2nd Series, vol. i. part 2. 
p- 293; also Mr. Weaver’s memoir, zbid. p. 367. 
