14 DESCRIPTION of the ~ 
breadth of this bed of whin is thirteen feet ; and where it fplits, 
its three branches are, fix, four, and three feet in diameter. The 
trend or ftretch of this bed is from weft to eaft; but upon the 
weit fide of the river, it curves fomewhat to the fouth-weft. Its 
compofition is nearly the fame with the three other beds of whin 
which I have before mentioned. It is of a brownifh-black co- - 
lour, and, when placed in certain directions, it fhows fpecks of 
luftre. It is vertical in its pofition, has a great degree of indu- 
ration, and its general fracture is roughly conchoidal. 
Aggregate Blue 
rock, Clay flate. 
The river. ~ 
Uron palling this bed of whin, the river ceafes to be deeply 
imbedded in the rocks ; but the aggregate rock and the clay flate 
ftill continue to be feen for a fhort diftance, in a fhelvy acclivi- 
ty, where they are loft to view in a long narrow plain, deeply 
covered with a bed of gravel, compofed of the debris of the in- 
terior mountains. The river here flows over this bed of gra- 
vel for a confiderable {pace ; and upon this narrow flat, we pafs 
through between two of the moft elevated points in the fouth la- 
teral range of this part of the Grampians. Although the obtru- 
fion of this mafs of gravel cuts off from infpection the continui- 
ty of the laft-mentioned rocks, yet the broken and abrupt fides 
of the mountains, clofe upon each hand, clearly points out, that 
this part of the fouth lateral range is entirely compofed of mica- 
ceous fhiftus. Here, we are deprived of the junction of the mi- 
caceous fhiftus with the two former rocks; and the lofs of all 
fuch 
