DIFFERENT PROVINCES OF NORTH AMERICA IN LATE PALEOZOIC TIME 71 



Redstone and Sewickley, two horizons which give evidence of extensive physical 

 changes. 



"The first of these horizons marks the general submergence which produced 

 the important limestones and calcareous shales which occupy much of the interval 

 between the Sewickley and the Waynesburg. We find no plants until we reach 

 the roof shales of the last-named coal. These shales, as we see from our analysis 

 of the table, contain nearly all the characteristic Carboniferous plants which 

 pass into the Upper Barrens, mixed with a great number of new forms. The 

 physical change here was not sufficient to entirely alter the flora. 



"The second horizon of changing conditions is found in, and immediately 

 above, the Waynesburg coal. In the rapid fluctuations in thickness of the clay 

 parting of this coal we see the first indications of unquiet, and of the approach of 

 that much greater disturbance which produced the important Waynesburg 

 sandstone, which in its extent and character gives ample evidence of widespread 

 change. 



"The Waynesburg sandstone often rivals the great Conglomerate sandstone, 

 which forms the base of the Productive Coal Measures in the amount of the 

 pebbles it contains. It is often 75 feet thick, and in expanse is coextensive 

 with the Upper Barrens. To form an idea, however, of the amount of change 

 required to produce this great mass, we must not simply consider the character 

 of the stratum per se, but must contrast it with the strata which immediately 

 precede it. Leaving out of view the Waynesburg coal, all the rocks for a con- 

 siderable distance under it are either limestones or fine-graned shales, which 

 show that the deposition of sediment must have taken place under conditions of 

 general quiet. The shale roof of the Waynesburg coal is not always present. We 

 sometimes find the sandstone lying immediately on the coal, and even descending 



into it. 



"When, then, in such localities we see the immense sandstone loaded with 

 pebbles lying immediately upon the coal with its subjacent fine-grained beds, we 

 are forcibly impressed with the magnitude of the change which has taken place. 

 The character of the pebbles also is significant. They are not of sandstone, but 

 of quartz, and hence must have been brought from remote localities. 



"Let us now consider what is the evidence from the lithology of the strata 

 of the Upper Barrens. Leaving out of consideration the finding of a conglomerate 

 at the base of the series, a feature which it has in common with the Permian of 

 Europe, we find in it a great deal of red shale, another feature of the Lower 

 Permian of Europe. These red shales occur in beds 20 feet to 30 feet thick, 

 sometimes commencing immediately above the Waynesburg sandstone. They 

 are a pretty constant feature, and are often, as at Bellton, several hundred feet 

 thick. These features, taken alone, are not entitled to much weight, except as 

 showing conditions unfavorable for the formation of coal, as they are found in the 

 barren portions of the Carboniferous formation proper. Besides these character- 

 istics which mark the Lower Permian of Europe, the Upper Barrens have some in 

 common with the Zechstein or Upper Permian, in the presence of a large amount 

 of limestone. 



"It is a significant feature that these limestones are devoid of marine fossils, 

 showing that the sea had access at no time during their formation. 



"The evidence from the total disappearance of coal beds in the higher portions 

 of Upper Barrens, and from the extremely small amount of it found in the lower 

 portions, is of more value, as indicating a great change from the conditions which 

 prevailed during the Carboniferous proper. The beds of coal gradually dis- 



