EECEEATIVE SCIENCE. 



237 



shape, and no such, special directions of 

 cleavage are exhibited, the lumps breaking 

 like any homogeneous stone with an earthy- 

 fracture. We have now then simply explained 

 the condition of coal, as well as why the hot 

 coals flake in our grates. 



But to return to our story. We have 

 pictured the forest growth of coal-material ; 

 we have told how the sluggish rivers wan- 

 dered down from the hills and plains, laden 

 with sludge, depositing heaps of branches, 

 stems, leaves, and trunks of pines and tree- 

 ferns amongst the rotting jungles of cala- 

 mites, lepidodendrons, and sigillarise over the 

 root-matted clay bottoms of sheltered marshes, 

 cut off from the wide and open sea by shingle 

 barriers and mud-banks ; how these condi- 

 tions alternated with influxes and over-cover- 

 ings of the sinking land by the salt sea, and 

 hence the alternations of the sandstones and 

 limestones with the seams of coal. But then 

 came a time when those regions were con- 

 vulsed and shattered by tremendous earth- 

 quakes and violent volcanic outbreaks. The 

 once continuous strata were dislocated, torn, 

 broken up, and faulted by the uplift or down- 



Example of " Upthrow"-fault, Ashby Coal-field. 1, 3, 3, 

 4, 5, 6, Seams of coal ;ab,cd, lines of fault ; b e, rock- 

 mass upthrown ; e f, present surface of country. 



throw of the vast disrupted rock-masses, or 

 squeezed, contorted, and thrown into anti- 

 clinals, and synclinals, into troughs, basins, 

 or those smaller curvatures known amongst 



miners as "horses."* Porphyry, basalt, and 

 other molten rocks were forced up into the 



Example of a smaU Coal-basin in the Ashby Coal-field. 

 1,2,3, curved seams of coal forming the basin; «/,■ 

 present surface of country. 



fissures, forming dykes, or were exuded as 

 lava-currents over the surface, or poured otit 

 on the sea-bottom, to be covered up by the 

 Permian conglomerates and sandstones, by 

 which the carboniferous deposits were suc- 

 ceeded, and which spread widely over the 

 coal-measures, when the latter, broken and 

 disrupted, had sunk beneath the waves. Thus 

 was the once luxuriant scene obliterated, and 

 the teeming soil made desolate and destroyed. 

 Yet in all this seeming disorder and violence 

 was the benevolence of the great Designer 

 made manifest : by this temporary destruction, 

 so to call it, of the carboniferous land, the 

 coal-stores have been preserved j by these 

 faults and dislocations the coal-measurea 

 have been made accessible over almost every 

 region to man, and by these dykes and fissure- 

 walls of molten matter the distinct and sepa- 

 rate areas of coal-tracts have been made 

 water-tight, and saved from inundation. 



So marked, so marvellous, are the inci- 

 dents in the formation, preservation, and the 

 accessible presentation of the numerous com- 

 partments of the great storehouses of fossil- 

 fuel, that we can hardly bring the mind 

 to think they have been efiected by the 

 natural operation of natural physical forces ; 

 but we seem almost to be compelled to rest 

 on an instinctive belief of a special ruling, or 



* These latter in some cases only. Usually these 

 minor subterranean ridges were formed during the 

 coal period by the pressure of forests or other heavy 

 weights causing a ridge on either side, equal to the force 

 of the pressure ; just as railway embankments, carried 

 over oozy tracts, will cause a " rising" on either side 

 of the line. 



