M. Kovanko’s General View of the Environs of Pekin. 249 
posed of different rocks. Three formations are distinctly ob- 
served in them. 
1st, Diorite ; 2d, compact grey limestone, which appears 
to correspond with the mountain or carboniferous limestone of 
England ; and, /as¢ly, the coal formation. 
A formation is besides observed, the independence of which 
is not altogether demonstrated. This is a species of conglo- 
merate intimately connected with the diorite, and which will 
consequently be described at the same time with that igneous 
rock. 
Dioritic Formation.—Diorite (greenstone) appears at the 
surface at the village of San-Ourad-Yan, and extends in as- 
cending the course of the river Bourbouse to the village of 
Van-Pin-Koon, a distance of more than 30 li. 
The diorite, small-grained, of a light green colour, is di- 
vided by fissures, giving it the form of beds inclined about 15° 
to the east. This rock is not very hard, except in its inferior 
portions; but as it acquires elevation, it loses its granular tex- 
ture, becomes friable and slaty, and passes into indurated 
clay containing nodules of quartz and of greenstone, which 
frequently exceed the size of a nut. In some places these no- 
dules occur only in veins in the friable dioritic mass, but some- 
times they are accumulated to such a degree as to form enor- 
mous masses of compact conglomerate. 
The thickness of the beds of the latter, which have the same 
inclination as the diorite, is about 1 sagéne. They alternate 
with ferruginous clay of a brownish red colour, forming in some 
places considerable elevations. This clay also contains nodules 
of quartz and of greenstone, which, by the decrease of their 
bulk, pass into a fine-grained sandstone without admixture, and 
are traversed in different directions by veins of white quartz. 
Every thing concurs to lead us to admit that this conglome- 
rate, so intimately connected with the diorite, does not, pro- 
perly speaking, belong to the dioritic formation, produced to 
all appearance by volcanic agency (porphyry conglomerates). 
In my opinion it constitutes a sedimentary rock in the fullest 
acceptation of that term, in the formation of which the dio- 
rite might have concurred. 
