OF A FORMER WORLD. 23 



joasts of Loch Long, and Loch Lomond, with nearly the 

 same inclination. The slate rocks of England underlaying 

 the silurian* system, are also of immense thickness. These 

 facts show that, previous to the carboniferous or coal era, 

 when the earth began to be adorned with vegetation, my- 

 riads of ages must have passed away." 



The carboniferousf formation excluding the mountain 

 limestone, and millstone grit,J measures 1900 yards in thick- 

 ness. Many of the limestones in this formation consist 

 almost entirely of organic remains. Beds of limestone, 

 30 feet thick, and totally composed of zoophytes and shells 

 of various kinds, are common in this formation : almost all 

 the sandstones contain the stems of trees belonging to 

 genera or species now unknown, and many of the clays 

 abound with the 'most delicate impressions of the fronds 

 and leaves of ferns, and other plants most delicately pre- 

 served : and fishes of enormous size are frequently met 

 with. || Coal itself is now universally acknowledged to 

 be of vegetable origin. The laminated nature of many of 



* Silurian from Silures, the name of the ancient inhabitants of 

 Wales. The term Silurian is given to those rocks which occured be- 

 tween the clay slate and the carboniferous system. 



f Carboniferous, containing coal. 



t Millstone grit, a series of rocks in England, which lie between the 

 mountain limestone and the coal measures, as the beds are called, which 

 contain workable seams of coal. 



Zoophite, a coral or animal plant. 



|| Fishes make their first appearance in the upper beds of the Silu- 

 rian rocks, but it is in the old red sandstone, where, on account of their 

 extraordinary and well-developed forms, the study of them becomes de- 

 finite and deeply interesting. " No two mineral formations contain tho 

 same fishes, the species in each being quite distinct from those of another. 

 With what interest then, must we regard these the first created of the 

 many thousands of species wnich, since the period of the old red sand- 

 stone, have moved through the waters of the ocean, preying on each 

 other, and otherwise performing the offices for which they were adapted 

 by their peculiar organizations in the economy of Nature." Agassiz. 



