566 DOMAIN VI. CARBONACEOUS. 



structed, that the chief beds of coal occur near 

 the mouths of great rivers, and in a kind of pro- 

 portion to their relative size. Thus the immense 

 Rhine, which seems, like many other powerful 

 streams, to have more than once altered its estu- 

 ary, has in its vicinity rocks of coal at least 80 

 feet in thickness; while more moderate strata 

 are found near the Rhone, the Clyde, the Forth, 

 the Tyne, the Severn. In some instances the 

 form of the coat district is that of an isosceles 

 triangle, the vertex being towards the sea. In 

 savage countries, darkened with immense fo- 

 rests, and where wood is only a superfluous 

 weed, the quantity of trees overturned by age, 

 tempests, and inundations, exceeds all imagina- 

 tion. On the Missouri, there is said to be a 

 bridge, not less than three miles in length, form- 

 ed by successive trunks of trees, which have been 

 stopped in their progress ; and the soil near its 

 mouth may be said to be formed of alternate 

 strata of timber and mud, which may probably 

 become coal and shale, for the use of nations to 

 be born, after a period of many thousand years, 

 and who, perhaps, may faintly trace in their 

 annals some memory of a celebrated ancient na- 

 tion called Britons. 



But this is merely an excursion of theory, and 

 the origin of coal is far from being precisely 

 ascertained. It occurs in such places, and with 



