354 Professor Jamesotfs Geogiiostical Description 
and compactness of the rock. Veins of different descriptions 
traverse these strata, and occasionally exhibit interesting geo- 
gnostical phenomena. 
The alluvial beds exhibit great variety in position and struc- 
ture, but these will form the subject of a separate communi- 
cation. 
The rocks of which the rising ground is composed, are the fol- 
lowing : Sandstone^ hituminous shale ^ slate-clay, clay-ironstone, 
coal, limestone, and greenstone. Of these the sandstone is the most 
abundant, and the coal and limestone the least frequent. The 
sandstone, bituminous shale, slate-clay, clay-ironstone, coal, and 
limestone, frequently pass into each other, thus proving that 
they are productions of the same era, and have been formed in 
the same manner. The greenstone occasionally exhibits inter- 
mixtures with the other rocks, but these are not so distinctly 
marked as in the sandstone or shale. 
1. Sandstone. — This rock is almost entirely composed of gra- 
nular concretions of grey and white coloured transparent or trans- 
lucent quartz, which are intermixed with scales of white-coloured 
mica, and grains of earthy-looking felspar. Sometimes there is a 
very inconsiderable clayey or calcareous basis or ground in which 
these grains are imbedded, but more frequently no basis is observ- 
able. These latter varieties, in hand specimens, are often so crys- 
talhne, that they cannot be distinguished from the quartz-rock 
of older formations. Indeed, the resemblance of sandstone to 
quartz-rock is so great, that it would be an improvement in geo- 
gnostical nomenclature to substitute the name Quartz-rock for 
Sandstone. 
It is distinctly stratified ; the seams of the strata sometimes 
extend through considerable masses of the rock; in other instan- 
ces they are of comparatively small extent, and not unfrequently 
one set of seams is included in others. In short, we observe in 
sandstone the same series of phenomena as occur in all rocks, 
from the most highly crystallised granite to the most perfect 
sandstone or clay-slate, thus rendering it probable that every 
rock is more or less distinctly stratified. Sometimes thick and 
short beds of sandstone are surrounded by thin horizontal strata 
of the same rock, or as in Pig. 2. Plate VIII. horizontal strata ct, 
