390 REPORT OF NATIONAL MUSEUM, 15*04. 



long period, but all referable to the «tuie geological epoch and anterior 

 to the elevation of the strata in which it occurred. 



After the deposition and injection ceased and the elevation of the 

 present continent had commenced, denudation, induced by a northerly 

 current, set in, the current itself being due to the flowing off of the 

 oceanic waters incidental to the elevation of the present continent. 

 Ify this denudation the soft shales and other materials were removed 

 and the trap ridges developed. Thus, deposition, intrusion, uplift, 

 and erosion were all included within a single epoch. 



Early speculations regarding the origin of the earth, though largely 



fanciful, were founded upon the brief outline of a series of events as 



chronicled in the first chapter of Genesis. Theories regarding earth 



development and its probable destiny other than its 



H. D. Rogers on the r .-,.,. . . 



Atmosphere of the catastrophic annihilation through Divine wrath, as a 



Coal Period, 1844. l , . " 



punishment tor sinful man, were slow to appear. 

 When such did appear, however, they were founded upon a much 

 more scientific basis. 



That a mutual reaction was going on constantly between the super- 

 ficial portions of the earth and its surrounding atmosphere was doubt- 

 loss realized by all of those who wrote on the weathering of rocks and 

 the formation of soils; but. so far as known to the present writer, II. I). 

 Rogers was one of the first of American geologists to show by direct 

 calculation that the earth had been in the past, as at present, robbing 

 the atmosphere of some of its constituent parts and gradually storing 

 them up in its solid crust/' 



At the Washington meeting of the American Association of Geolo- 

 gists and Naturalists in May, 1844, Professor Rogers submitted a com- 

 munication on the probable constitution of the atmosphere at the period 

 of the formation of the coal. He estimated that the amount of carbon 

 existing in the atmosphere to-day in the form of carbonic acid would 

 be only sufficient to furnish through vegetable action about 850,000,000 

 tons of coal, while the probable quantity of this substance in existence, 

 all of which must have been elaborated from the ancient atmosphere, 

 was nearly 5,000,000,000 tons; that is to say, about six times what the 

 present atmosphere would produce. So great a reduction in the car- 

 bonic acid, implying a corresponding augmentation of oxygen, is felt 

 to be a matter of great interest in geology, as showing that every modi- 

 fication in the constitution of the air had adapted it to the development 

 of animals progressively higher in the scale of organization. 



Of all the New England States Vermont was the last to become 

 infected with a desire for a geological survey, and it was not until 



«Vanuxem in 1827, while connected with South Carolina College, pointed out the 

 probable change in the atmosphere during geologic time through the absorption by 

 the earth of nitrogen ami oxygen, and also the probability of a warm, moist climate 

 during the period of coal formation. (American Journal of Science, XII, 1827.) 



