GEOLOGY. 



conglomerates; rain-showers fell, and left their 

 impressions on the sandy bays pelted with their 

 drops; forests of sea-weed waved in the green 

 waters and on the rocky reaches ; and shells 

 adorned the rocks. Into the seas flowed great 

 rivers, whose banks were fringed with reeds and 

 flags ; ferns waved on the hill-side, tree-ferns 

 reared aloft their feathery plumes, and broad- 

 leaved plants clothed the surface of the landscape ; 

 while large reptiles roamed through the forests, or 

 crushed the reeds by the river-sides. 



V. CARBONIFEROUS SYSTEM. 



Description. Above the Devonian rocks lies a 

 series of strata perhaps more generally known 

 than any other, as they afford us what is so neces- 

 sary to our comfort, the remarkable 

 combustible stone called coal. They 

 receive the name Carboniferous^- from 

 the fact that they contain coal, although 

 they furnish many other important pro- 

 ducts. These rocks are found in most 

 regions of the globe ; but in none are 

 they more fully developed, compared 

 with the size of the country, than in the 

 British Isles. They consist of sand- 

 stones, limestones, shales, clays, iron- 

 stone, and coal. The sandstone is of 

 various qualities and colours, some of it 

 very valuable and durable ; the beauti- 

 ful stone of which the New Town of 

 Edinburgh is built is from this system. 

 The limestones are largely developed, 



numerous and important. We find coal of alP 

 kinds for household purposes and gas; iron, sand- 

 stone, limestone, and fireclay. From the shales, 

 are obtained alum and the remarkable paraffine 

 oil So abundant in America and elsewhere 

 is this ancient oil, that when the earth is bored 

 a flood of it issues forth yielding thousands o 

 gallons daily. 



Organic Remains.~T:te organic remains found 

 in this system are very abundant and remarkable 

 Plants are numerous, varied, and beautiful. Ferns', 

 are found with the most perfect fronds, as dis- 

 tinctly traced upon the rock as a modern dried 

 fern on the pages of a book. We find also large 

 and beautiful club-mosses exquisitely exhibited 

 But the most luxuriant and beautiful of all are the 

 great pine-like araucarias, the fruit 1 of which. 



3 4 



Carboniferous Plants. 

 Branch of AsterophylUtesfoliosus, a kind of reed; 2, 3, 4, Ferns. 



and are of the greatest service for building and 

 agriculture. The shales have of late become very 

 valuable, as from them are distilled oils and other 

 substances, including the celebrated paraffine oil 

 and candles. The ironstone is of the 

 very greatest value, and contributes very 

 largely to England's wealth. 



It must not be thought that coal is 

 found only in the Carboniferous rocks. 

 Coal, being chiefly compressed vegetable 

 matter, may be found in any rock-system 

 in which plants are preserved. It is 

 accordingly found in other systems, and 

 often in great abundance. For example, 

 the coal-fields of Virginia, some thirty 

 or forty feet thick, belong to the Oolitic ; 

 and coal of various kinds can be ob- 

 tained, more or less, from most systems. 



The same is true of other products, 

 such as limestone, sandstone, and iron, 

 which last, though found in greatest 

 abundance in this system, yet occurs 

 in many others from the earliest. 



The Coal-strata are divided into three great 

 groups the Upper and Lower Measures, and a 

 thick deposit of limestone, which separates them, 

 known as the Mountain or Carboniferous Lime- 

 stone. The Upper Coal-measures are also called 

 the True Coal-measures, as they contain the great- 

 est amount of workable coal; the Lower Coal- 

 measures consist chiefly of sandstones and shales. 

 The Mountain Limestone is so called because 

 where it is most largely developed, as in York- 

 shire, it rises into hills with great limestone cliffs. 



The industrial products of this system are 



1 From Latin carlo, coal, vn&fcro, to bear. 



may, in some places, be gathered by the bushel ;. 

 the tree-ferns, and tall reeds that grew in bound- 

 less swamps and jungles along the banks of the- 

 rivers, that swept in mighty volume to the carbon- 



Carboniferous Trees. 



Sigillaria ; 2. Stigmaria, root of Sigillaria, with rootlets attached, 

 and pith ; 3. Calamite ; 4. Lepidodendron. 



iferous seas. We see the lepidodendron * or scale>- 

 tree, with its pine-like leaves, beautiful scaly 

 bark, and great cones, 3 from which the seed of 

 the ancient pine may be gathered in hundreds to 

 this very day; the sigillaria* or seal-tree, with 

 its seal-stamped trunk and great pitted and 

 branched root, called stigmariaj' long thought to- 

 be a tree of a different species ; the calamite* or 



* Called Trigonocarpum, from Greek trrit, three, ftml. 

 comer, and carpos, fruit. 



* From Greek lefts, -idoi, a scale, and dendron, a tree. 



8 Called lepidostrobi, from Greek Ufa, -idos, a scale, an* 

 ttrobilos, a fir-cone. 

 From Latin sigilla, a seal. * From Latin ttifma, * mark. 



* From Latin calamus, a reed. 



II 



