of the Rocks of Shetland. S09 
cottglomerate rcxjk. Thus, whilst the strata of sandstone dip to 
the east, those of the conglomerate rock dip to the west. Now 
the strata of the conglomerate rock, where observed in contact 
with those of the granular quartz, seem perfectly vertical ; but 
on crossing them for a distance of a few yards only, they are im- 
mediately observed to form less angles with the horizon, until 
they acquire a position nearly horizontal. Here the vertical 
position of the conglomerate strata, in contact with the granular 
quartz which dips to the east, seems an arrangement that is in 
conformity to an abrupt or vertical precipice, formed by the 
outgoing edges or escarpments of the strata of granular quartz, 
' — with which vertical precipice, the contiguous strata of the 
conglomerate rock appear to range. Such a structure, by which 
a stratum is affixed to its inferior edge in a vertical position, 
does by no means bear the marks of a deposit calculated to fill up 
hollows or valleys. The explanation that I would give of this 
vertical position is, that the precipice of the granular quartz 
had influenced the mode in which the conglomerate strata were 
consolidated, according to certain finite laws of crystallization, 
but the change in the inclination of tlie conglomerate strata, 
which on crossing them are found to acquire nearly a horizontal 
position, and to dip to the west in a direction contrary to that of 
the granular quartz, is an arrangement tending to show, that 
the density of the strata had increased in proportion to their 
depth, and that the laws of gravity had been opposed to those 
of chemical affinity. It is thus that an accumulation of matter 
from below, produced by an increased density of the strata, 
would, by gradually elevating strata in the order of succession in 
which we meet them, have produced a position nearly horizontal. 
Bthly^ The next circumstance to’ be noticed in the conglome- 
rate rocks, is, that they do not graduate into their subjacent 
rocks by an interchange of substance. The attachment is very 
firm, showing that an action of a chemical nature, probably as- 
sisted by compression, may have induced it. But the line mark- 
ing the boundary of each rock is perfectly distinct. It may, 
however, be anticipated, that an appearance diametrically oppo- 
site to this occurs elsewhere in Shetland ; conglomerate strata im- 
perceptibly graduating into thoso of quartz, which are fundai* 
mental to them. 
