212 UPRIGHT FOSSIL TREES. [CHAP. XV. 



this coal was of newer date than that of the Appalachians, and 

 was about the age of the Oolite or Lias, a conclusion which, after 

 a careful examination of the evidence on the spot, and of all the 

 organic remains which 1 could collect, appears to me to come 

 very near the truth. If we embrace this conclusion, these rocks 

 are the only ones hitherto known in all Canada and the United 

 States, which we can prove, by their organic remains, to be of 

 contemporaneous origin with the Oolitic or Jurassic formation of 

 Europe. The tract of country occupied by the crystalline rocks, 

 granite, gneiss, hornblende-schist, and others, which runs parallel 

 to the Alleghariy Mountains, and between them and the sea, is 

 in this part of Virginia about seventy miles broad. In the midst 

 of this area occurs the coal-field alluded to, twenty-six miles long, 

 and varying in breadth from four to twelve miles. The James 

 river flows through the middle of it, about fifteen miles from its 

 northern extremity, while the Appomattox river traverses it near 

 its southern borders. The beds lie in a trough (see section, fig. 

 4, p. 213), the lowest of them usually highly inclined where they 

 crop out along the margin of the basin, while the strata higher 

 in the series, occupying the central parts of the area, and which 

 are devoid of organic remains and of coal, are nearly horizontal. 



A great portion of these coal-measures consists of quartzose 

 sandstone and coarse grit, entirely composed of the detritus of the 

 neighboring granitic and syenitic rocks. Dark carbonaceous 

 shales arid clays, occasionally charged with iron ores, abound in 

 the proximity of the coal-seams, and numerous impressions of 

 plants, chiefly ferns and Zarnites, are met with in shales, to 

 gether with flattened and prostrate stems of Calamites and Equi- 

 setum. These last, however, the Calamites and Equisetum, are 

 very commonly met with in a vertical position, more or less com 

 pressed perpendicularly. I entertain no doubt that the greater 

 number of these plants standing erect in the beds above and 

 between the seams of coal which I saw at points many miles 

 distant from each other, have grown in the places where they 

 are now buried in sand and mud, and this fact implies the 

 gradual accumulation of the coal-measures during a slow and 

 repeated subsidence of the whole region. 



