COAL FORMATION. 



were raised up, and at others lowered down, so that they became 

 more or less oblique, and often seem to be, as it were, folded on 



themselves ; it is also remarked that 

 frequently a certain extent of the mass 

 formed by these layers has been sepa- 

 535-* rated from neighboring parts by a sort 

 ~A^i of split or cleft, and elevated or de- 

 __ ^g - pressed to a different level ; conse- 

 Fig. 55. Fault. quently the beds of coal are suddenly 



interrupted at these points, and are 



found further on at a different height. These geological accidents 

 are designated by miners under the name of faults, (Jig. 55). 



Speaking of the origin and nature of coal, Dr. Bucklanct remarks, " The 

 most early stage to which we can carry back its origin, was among the 

 swamps and forests of the primeval earth, where it flourished in the form 

 of gigantic Ca'lamites, and stately Lepidode'ndra, and Sigilla'ria. From 

 their native bed, these plants were transported into some adjacent, lake, or 

 estuary, or sea. Here they floated on the waters, until they sank saturated 

 to the bottom, and being buried in the detritus of adjacent lands, became 

 transferred to a new estate among the members of the mineral kingdom. 

 A long interment followed, during which a course of chemical changes, and 

 new combinations of their vegetable elements, converted them to the mine- 

 ral condition of coal. By the elevating force of subterranean agency, 

 these beds of coal have been uplifted from beneath the waters, to a new 

 position in I'iie hills and mountains, where they are accessible to the industry 

 of man. From this fourth stage, coal has been removed by the labours of 

 the miner, assisted by the arts and sciences, that have co-operated to pro- 

 duce the steam-engine and the safety-lamp. Returned once more to the 

 light of day, and a second time committed to the waters, it has, by the aid 

 of navigation, been conveyed to the scene of its next and most considerable 

 change by fire ; a change during which it becomes subservient to the most 

 important wants and conveniences of man. In this seventh stage of its 

 long and eventful history, it seems, to the vulgar eye, to undergo annihila- 

 tion ; its elements are, indeed, released from fhe mineral combinations 

 which they have maintained for ages, but their apparent destruction is only 

 the commencement of new successions of change and of activity. Set free 

 from their long imprisonment, they return to their native atmosphere, from 

 which they were absorbed by the primeval vegetation of the earth. To- 

 morrow they may contribute to the substance of timber in the trees of our 

 existing forests; and, having for a while resumed their place in the living 

 vegetable kingdom, may, ere long, be applied a second time to the use and 

 benefit of man. And when decay or fire shall once more consign them to 

 the earth, or to the atmosphere, the same elements will enter on some fur- 

 ther department to their perpetual ministration in the economy of the ma- 

 terial world." 



21. A part of this grand upturning of the coal formation has 

 not disturbed the more recent strata by which it may be covered, 

 and consequently it must have been effected at the close of the geo- 

 logical period whose history we have just studied. 



20 How were the coal-measures deposited ? What is meant by a Fault? 

 21. Has the disturbance of the coal strata affected the strata subsequently 

 deposited abcve them ? 



