ROCKS OF SCOTLAND. 387 
attempted restoration of the probable scenes and events of the 
period, in what is now Scotland. 
For many ages, a wide ocean, from which the eye fails to 
see any shore, or the sounding-lead to find any bottom, rolls 
over what is now our country. Its profound depths, wrapped 
up in darkness, sink beneath the zero line of animal or vege- 
table life; and the fine gray mud, or light micaceous sand, that 
settles upon its unseen bottom, as the impalpable dust that 
mottles the sunbeam sinks on the floor of some deserted hall or 
old haunted chamber, scarce forms, after the lapse of years, a 
layer as thick as the roofing slate into which, in these latter 
times, we find it consolidated. Gradually, however, and per- 
sistently, the deposition goes on. Besides, under the deep- 
seated impulsions of the Plutonic forces, vigorous in their early 
youth, there is a general rising of the platform. At length the 
light of day reaches it through the lessening space, in a dim 
green twilight, and it becomes a scene of organic existence. 
Vast fields of nameless algze, still represented amid the rocks 
by our anthracite bands, embrown for many leagues the ocean 
bottom ; and millions of zodphytes, not higher in the scale than 
the modern pennatuladz, which they not a little resemble, crowd 
every square rood of surface. And here, at wide intervals, 
some ancient terebratula fastens its fleshy cable to the rock, or 
there some lingula stands erect, flower-like, in its horny stem. 
There are changes taking place, now gradual, anon abrupt. 
At one time death itself serves but to furnish fresh platforms 
for new life; at another, through some subsidence in the gen- 
eral floor, the zero line of vitality is again reached, and over 
perished myriads, the dead, sluggish strata settle down. At 
length, when unreckoned centuries — mayhap hundreds of cen- 
turies — have passed, the middle ages of the Lower Silurian 
period are ushered in; and when the Llandeilo flags and Bala 
limestones are in the course of deposition in what is now the 
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