394 IN TROUGHS OR BASINS. 



depths, wherein they were formed ; and it required the ex- 

 ercise of some of the most powerful machinery in the Dyna- 

 mics of the terrestrial globe, to effect the changes that were 

 requisite to render these Elements of Art and Industry ac- 

 cessible to the labour and ingenuity of man. Let us briefly 

 examine the results that have been accomplished. 



The place of the great Coal formation, in relation to the 

 other series of strata, is shown in our first section (PI. 1. 

 Fig. 14.) This ideal section represents an Example of dis- 

 positions which are repeated over various areas upon the 

 crust of the Globe.* 



The surface of the Earth is found to be covered with a 

 series of irregular depressions or Basins, divided from one 

 another, and sometimes wholly surrounded by projecting 

 portions of subjacent strata, or by unstratified crystalline 

 rocks, which have been raised into hills and mountains, of 

 various degrees of height, direction and continuity. On 

 either side of these more elevated regions, the strata dip 

 with more or less inclination, towards the lower spaces be- 

 tween one mountain range and another. (See PI. 1.) 



This disposition in the form of Troughs or Basins, which 

 is common to all formations, has been more particularly 

 demonstrated in the Carboniferous Series, (See PI. 65. Fig^ 

 1, 2, 3.) because the valuable nature of beds of Coal often 

 causes them to be wrought throughout their whole extent. 



One highly beneficial result of the basin-shaped disposition 

 of the Carboniferous strata has been, to bring them all to 

 the surface around the circumference of each Basin, and to 

 render them accessible, by sinking mines in almost every 

 part of their respective areas; (See PI. 65. Figs. 1, 2, 3.) 

 An uninterrupted inclination in one direction only, would 

 have soon plunged the lower strata to a depth inaccessible 

 to man. 



• The Coal Formation is here represented as Iiaving partaken of the same 

 elevatory movements, which have raised the strata of all formations towards. 

 the mountain Ridges, ths^t separate one basin from another basin. 



