86 * PROCEEDINGS OF THE ACADEMY OF [1892. 



ness and value, is what might have been antecedently expected as 

 soon as the geological history of coal became certainly known. At 

 the time of the coal deposits neither the Allegheny nor the Rocky 

 Mountains existed. South and west of the Green Mountains of 

 Vermont the continental area Avas flat and low and being without 

 adequate drainage constituted here a vast swamp, there a succession 

 of small morasses, constantly enduring slow and slight changes of 

 elevation ; now for a time and in places sufficiently above water to 

 permit the growth of the redundant flora incident to such condi- 

 tions, then sufficiently below to destroy vegetable life and cover its 

 remains with deposits of sand of varying thickness, sometimes in fresh, 

 sometimes in sea water. In some places ages elapsed before another 

 emergence made renewed vegetable growth possible, in others sub- 

 sidences and emergences succeeded each other with comparative 

 rapidity, as now evinced by the respective thickness of the carbon- 

 aceous beds and the intervening sandstones, a-s well as by the succes- 

 sion of fossil species of plants and animals. 



Thus the secular succession and separation of the coal seams, and 

 the large proportion of those whose thinness deprives them of 

 economic value is intelligibly explained by the then condition of 

 land and water over this area, and the repeated though slow and 

 slight changes in their relative level, while the destruction of a 

 large part of such seams as were once valuable has been plainly 

 due first to th*e extensive and violent disturbance of which the con- 

 dition of the beds themselves supplies ample evidence, and next to 

 more recent erosion on a stupendous scale. 



It is unnecessary to dilate upon these elementary and well-known 

 circumstances, because they have been for a long time very com- 

 pletely established and are fully set forth in all standard works on 

 the subject, but so much seemed essential to remind the reader of 

 the causes of the preponderance of thin and worthless seams, of the 

 great irregularity both in thickness and condition of the compara- 

 tively few workable ones, the injury and even ruin sustained by 

 many, and finally of the tremendous destruction and loss by 

 erosion. 



While there is a large amount of detached information available 

 respecting the number and dimensions of workable seams at various 

 points, there has been no such systematic collation of them as may 

 serve for any precise generalization susceptible of jDroof, nor is it 

 probable that such will be possible for some years to come. Never- 



