t 



E. C. Case — Amphibian Fauna at Linton^ Ohio. 133 



'Inimns' soil, and even destroyed, so that the formation of 

 a thick bed of coal was impossible, unless the rise of the water 

 level, usually by accelerated submergence, was brought about. 

 The formation of a thick bed of coal is therefore seen to indi- 

 cate in general the maintenance for a long period of an approx- 

 imate balance between the rate of peat accumulation and the 

 rise of the water, so as to maintain a depth of water favorable 

 for the growth of the vegetation and its preservation as peat. 



In confirmation of the views of many geologists the writer's 

 observations of the horizontally extensive coal beds in the 

 American fields lead him to conclude that the peat-forming 

 vegetation, which was probably largely vascular, grew in place 

 over nearly all of the areas of these coal beds and that it occu- 

 pied these areas almost continuously during the deposition of 

 the peat except at times marked by the inundation in washes 

 represented by the clay or shale partings in the coal. In other 

 words, most of our commercial coal has been formed from 

 plants that grew above the surface of the peat, and is of autoc- 

 thonous origin. Coal that may be attributed to the mere 

 accumulation of drift vegetation is, according to the author's 

 observations, very restricted in area and variable in thickness, 

 and much of it is too high in ash to be of value. 



In certain regions in which the water was quiescent, but of 

 too great depth for occupation by vegetal growth, bituminous 

 shales and black carbonaceous muds, many containing marine 

 or brackish water shells, seem to have been deposited in many 

 places, the state of the organic material — that is, its stage of 

 decay — being dependent largely upon the rate of accumulation 

 of the vegetal debris and the supply of oxygen. At many 

 points small areas of open water, temporary in duration, occur- 

 ring in the midst of the swamps were marked by the concen- 

 tration of spores, resins, waxes, etc., forming cannel layers or 

 lenses, the more destructible matter being lost by decomposi- 

 tion, which here again is dependent on the oxygen supply and 

 rate of delivery of the plant debris. In other cases very 

 restricted areas of open water (not occupied by vascular plant 

 growth) whose stagnant depths were more toxic seem to have 

 favored the accumulation, without decay to the point of destruc- 

 tion, of plankton of various types, as well as of wind-borne 

 spore materials forming boghead, and boghead-can n el coal. In 

 none of the important and widely extended coal beds examined 

 by the writer has he observed any lenses or intercalated bodies 

 of coal that may be interpreted as masses, floating islands, or 

 rafts of vegetation somewhat abruptly submerged, in accord- 

 ance with the hypothesis proposed by numerous writers." 



Elsewhere David White speaks of the region as " one vast 

 peneplain." 



