B19 THE OLD RED SANDSTONE. 
ert country, with its wide wastes of unprofitable sand, its 
broken citadels and temples, its solitary battle-plains, and its 
gloomy streets of cavernel and lonely sepulchres ; and quite 
another to record its history during its days of smiling fields, 
populous cities, busy trade, and monarchical splendor. We 
pass from the dead to the living—from the cemetery, with 
its high piles of mummies and its vast heaps of bones, to the 
ancient city, full of life and animation in all its streets and 
dwellings. 
Two great geological periods have already come to their 
close ; and the floor of a widely-spread ocean, to which we 
can affix no limits, and of whose shores or their inhabitants 
nothing is yet known, is occupied to the depth of many thou- 
sand feet by the remains of bygone existences. Of late, the 
geologist has learned from Murchison to distinguish the rocks 
of these two periods —the lower as those of the Cambrian, 
the upper as those of the Silurian group. The lower— rep- 
resentative of the first glimmering twilight of being — of 
a dawn so feeble that it may seem doubtful whether in reality 
the gloom had lightened — must still be regarded as a period 
of uncertainty. Its ripple-marked sandstones, and its half 
coherent accumulations of dark-colored strata, which decom- 
pose into mud, show that every one of its many plains must 
have formed in succession an upper surface of the bottom of 
the sea; but it remains for future discoverers to determine 
regarding the shapes of life that burrowed in its 00ze, or ca 
reered through the incumbent waters. In one locality it 
would seem as if a few worms had crawled to the surface, 
and left their involved and tortuous folds doubtfully impressed 
on the stone. Some of them resemble miniature cables, care- 
lessly coiled; others, furnished with what seem numerous 
legs, remind us of the existing Nereidina of our sandy 
