CHAP. XV.] COAL OF OOLITIC PERIOD. 211 



I had stopped at Richmond on my way south, for the sake of 

 exploring geologically some coal mines, distant about thirteen 

 miles from the city to the westward. Some of the largest and 

 most productive of these, situated in Chesterfield County, belong 

 to an English company, and one of them was under the manage 

 ment of Mr. A. F. Gifford, formerly an officer in the British 

 army, and married to a Virginian lady. At their agreeable 

 residence, near the Blackheath mines, we were received most 

 kindly and hospitably. On our road from Richmond, we passed 

 many fields which had been left fallow for years, after having 

 been exhausted by a crop of tobacco. The whole country was 

 covered with snow, and, in the pine forests, the tall trunks of the 

 trees had a white coating on their windward side, as if one half 

 had been painted. I persevered, nevertheless, in my examination 

 of the mines, for my underground work was not impeded by the 

 weather, and I saw so much that was new, and of high scientific 

 interest in this coal-field, that I returned the following spring to 

 complete my survey. 



There are two regions in the state of Virginia (a country 

 about equal in area to the whole of England proper), in which 

 productive coal-measures occur. In one of these which may be 

 called the western coal-field, the strata belong to the ancient 

 carboniferous group, characterized by fossil plants of the same 

 genera, arid, to a great extent, the same species, as those found 

 in the ancient coal-measures of Europe. The other one, wholly 

 disconnected in its geographical and geological relations, is found 

 to the east of the Appalachian Mountains, in the middle of that 

 granitic region, sometimes called the Atlantic Slope. * In con 

 sequence of the isolated position of these eastern coal-beds, the 

 lowest of which rest immediately on the fundamental granite, 

 while the uppermost are not covered by any overlying fossiliferous 

 formations, we have scarcely any means of determining their 

 relative age, except by the characters of their included organic 

 remains. The study of these, induced Professor W. B. Rogers, 

 in his memoir, published in 1842,f to declare his opinion that 



* See geological map of the U. S. in my &quot; Travels in North America,&quot; 

 vol. i. and ii. p. 92. t Trans, of American Geologists, p. 298. 



