454 



Miscellaneous. 



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 nodules occur only in veins in the friable dioritic mass, 

 but sometimes 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 incli- 

 nation as the diorite, is about 1 sagene. They alternate with ferru- 

 ginous clay of a brownish red colour, forming in some places consider- 

 able 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 conglomerate, so 

 intimately connected with the diorite, does not, properly speaking, 

 belong to the dioritic formation, produced to all appearance by volca- 

 nic agency (prophyry conglomerates). In my opinion it constitutes 

 a sedimentary rock in the fullest acceptation of that term, in the forma- 

 tion of which the diorite might have concurred. 



It would appear that the conglomerate is more recent than the 

 diorite, and that it would be better to class it in the coal-formation, 

 considering it as an equivalent to the old red sandstone of England. 



The diorite cropping out at the base of the mountain Lao-Goua-Shan 

 to the west of Van-Pin-Koon, as well as the conglomerate which over- 

 lies it, has a dip nearly vertical. This peculiar inclination might be 

 attributed to some more recent revolution which these rocks have 

 undergone, occasioned apparently by the dioritic porphyry which rises 

 from beneath the diorite, but which, however, does not form any con- 

 siderable masses. 



Vertical seams of coal lie in some places between the diorite and 

 the conglomerate, having the latter for the roof and the former for the 

 floor. 



Slate-clay, which has the properties of a combustible slate, from the 

 great quantity of bitumen it contains, forms a border to the coal on the 

 side of the roof. 



The border on the side of the floor, although equally composed 

 of slate-clay, contains less bitumen, and has not so much lustre as 

 the former. This coal very much resembles anthracite, because it is 

 shining, of compact texture, difficult to ignite, does not flame in 

 burning, or give out any smoke. Its substance is entirely homogene- 

 ous, and every thing respecting it leads to the belief that there had 

 been a great development of heat at the period of its formation. 



