378 THE FOSSILIFEROUS 
compared with its many-colored porphyries, its granites, and its 
quartz-rocks. In the Forfarshire Conglomerate, the prevailing 
rocks are hard porphyries, of an -infinite variety of hue, and 
indistinguishable in their composition from the porphyries of 
Ben Nevis and Glencoe; in the Conglomerate of Cromarty 
and Ross, a decaying granite, red like that of Peterhead, but 
as finely grained as that of Aberdeen, blent with red quartz- 
rock and red granitic gneiss, is the prevailing stone; in that of 
Orkney, as exhibited in the neighborhood of Stromness, the 
prevailing rock is also a red granite, somewhat larger in its 
grain, and more durable, than the Cromarty one. The stone 
which composes many of these inclosed pebbles can no longer 
be found in sttw; and a good representative collection of at 
least the classes of the rocks which they exemplify would serve 
to show the nature of the framework of that ancient unknown 
land to whose existence the Great Conglomerate bears evi- 
dence; and which —as over many thousand square miles the 
pebbles present the worn and rolled character—must have 
been exposed, zone after zone, during a protracted period of 
gradual depression, to the incessant wear of the ocean. ‘The 
Conglomerate seems to have been exposed in an after period 
to intense heat. We find many of its hardest pebbles bent 
and indented, as if they had been reduced to the consistency 
of dough, or distorted by miniature faults, which scored their 
lines of fracture with the ordinary slicken-sided markings, when 
they were in a state viscid enough to re-unite. The fact 
would have been deemed a great one during the heat of the 
controversy waged in this city between the antagonistic schools 
of Hutton and Werner; but it is not less interesting now, when 
it can be looked at more quietly ; and so I have given to a series 
of the pebbles which illustrate it a place in my collection. 
Above the upper beds of the Great Conglomerate, at distan- 
ces varying from forty to a hundred and sixty feet, the fishes 
