620 STEVENSON— FORMATION OF COAL BEDS. [November 3. 



The portion of Holland considered in Lorie's tabulated records 

 is not less than 1,500 square miles ; a more extensive area in Belgium 

 shows the existence of covered peat deposits and this condition 

 reaches far over into France, for, at Cotentin in Normandy, the 

 peat, 20 meters thick, is covered with 3 meters of marine sand. One 

 has in this region an area, almost as great as that of the Everglades 

 in Florida, in which the existence of buried peat bogs has been 

 proved, some of them having been traced continuously in a great 

 part of the region. How great the total area may be, has not been 

 ascertained, but it is very much greater than that which has been 

 studied in detail. 



The change in structure and composition of peat, as the depth 

 increases, has been referred to more than once in the preceding 

 pages. Evidently the older the peat, other things being equal, the 

 more thoroughly the material is disintegrated, li compacted by 

 pressure and the removal of water, it assumes the appearance of 

 brown coal and does not regain plasticity, as appears from the de- 

 scriptions by Dawson and Lesquereux, to which many others might 

 have been added. It is certain that some constituent, once soluble 

 in water, has become insoluble, as soluble silica, once dried, becomes 

 insoluble. When the deposit, exclusive of enclosed wood, has been 

 reduced to mature peat, one must resort to chemical reagents and to 

 the microscope in order to ascertain the component materials. Those 

 bring to view a structure, a physical composition, which is wholly 

 similar to that which Grand" Eury gives for coal studied after the 

 same method. It is a mass of disintegrated fragments, held together 

 by a fundamental material, much of which was originally flocculent. 

 The older quaternary peats show much variation ; that described by 

 Dawson has little which suggests peat to the unaided eye; but there 

 are others which so much resemble the newer peats that, were it not 

 for the presence of extinct mammals and the great thickness of 

 cover, one might hesitate before deciding that they are not of recent 

 origin. There are still others, which in the several layers exhibit 

 great variations, some being of comparatively unchanged peat, while 

 the material in others has lost all of the original macroscopic 

 features. 



218 



