6l2 



THE POPULAR SCIENCE MONTHLY. 



bed awaiting only the i)roper manipulation to be converted into useful 

 fuel at the other. That peat is formed of plants, and largely of plants 

 that accumulate just where they grow, can be no longer questioned. 



In the swamps and bayous of the moist regions of the South, pure 

 vegetable matter, having the appearance and properties of peat, may 

 often be found in the very act of accumulation. It frequently occurs 

 in immense beds, and it requires no trained observation to see that, in 

 addition to the remains of the ordinary low marsh-jjlants, it is made 

 up of the ruins and refuse of swamp-loving forest-trees. Now, all about 

 the flanks and spurs of the Rocky Mountains, with greater or less inter- 

 vals, from New Mexico to far beyond the northern limits of the United 

 States, there are found beds of coal of peculiar quality. This coal is 

 covered up with hardened mud containing shells and bones of aquatic 

 animals, and everything about it suggests that the coal-making material 



was somehow sunk beneath the waters of an 

 old lake, and was buried under the gradually 

 increasing bed of mud with which the old 

 lake-basin was finally filled. But the point of 

 interest is this : that in many places the Rocky 

 Mountain coal has reached a stage of decom- 

 position not so very much in advance of the 

 humus and peat of our modern swamps and 

 bayous. We might, indeed, hesitate about 

 calling some portions of it coal at all for 

 the original structure is almost perfectly pre- 

 served yet it must be admitted that for the 

 most part the decomposition has advanced far 

 enough to produce an article that deservedly 

 ranks as coal. In the light of what may be 

 observed going on in every favorably situated 

 swamp to-day, the source of the material and 

 the method of accumulation of the Rocky 

 Mountain coal can hardly be doubtful. I 

 need not weary you by leading you step by 

 step through all the known coal-fields that illustrate the different 

 stages in the process of coal-formation. It will be sufficient to say 

 that a perfect gradation may be traced from the lignite, as it is called, 

 of the Rocky Mountains to the purer and more perfect coal of the 

 Mississippi Valley ; and so, even setting aside the internal evidence of 

 our Iowa coal, we are compelled to believe that it is simply one of the 

 terms of the same series to which the lignite and the peat belong, and 

 that the initial term of that series is to be looked for in the living 

 vegetation of modern marsh and forest. 



The conclusion is interesting, though to an intelligent audience it 

 could hardly be called unexpected. The method of reaching it is 

 worthy of notice, and points some important lessons. Though the 



Fig. 3. Restoration of a Lepi- 

 dodendkon. 



