Geology of High Teesdale. 175 
whom I was accompanied, described them te me by the name 
of the slaggy beds. The confused mass under the trap, in Sec- 
tion 3, seems to be formed by the irregular blending of two or 
three strata, by an action partly mechanical, and partly chemical. 
In the cellular beds, the most solid portions differ from each 
other in hardness and in colour, so that in one specimen we may 
find substances resembling hornstone, chert, or porcelain jasper ; 
sometimes appearing rudely arranged in concentric layers which 
run in irregular curves round the cavities of the mass. All these 
substances are hard, and under the hammer fly into splinters, 
which are translucent at the edges. Small fragments of them 
readily fuse into a whitish glass with minute air-bubbles, or 
into a light coloured enamel. The cells are very irregular in size 
and shape, varying from the fraction of an inch to three or four 
inches in diameter; and they are lined and partly filled with 
a rough spongy mass, which, im some specimens, does not appear 
to differ from the more solid part of the rock; but in others, is 
mixed with a dark greenish substance, which readily yields to 
the knife, and fuses into a dark coloured glass. It is generally 
crystalline in structure, but no distinct cleavages could be obtained 
from it, and it sometimes passes into a compact mass of the same 
colour. I do not think that it is allied to green earth. 
In the same cells are also found minute garnets with per- Gm 
fect rhombic faces, which are sometimes of an olive-brown, but 
mere frequently of a dark olive-green colour. By breaking up 
a great many masses on the spot, I obtained a few crystals, 
which it was impossible to mistake ; and some almost microscopic 
specimens, have been since examined by Mr. Phillips, who found 
that they exhibited the angles of garnet. The existence of gar- 
nets in this singular locality, was first discovered by the Rev. 
J. Harriman, (Sowerby’s Brit. Min. Vol. II. p. 37.) And under 
exactly similar circumstances of association, very fine garnets 
