SECONDARY COAL-FIELDS. 149 



dia ; in Burma, Borneo, and Labuan ; in New Zealand ; 

 Natal in South Africa; Vancouver Island, and British 

 Columbia ; at Eichmond in Virginia ; and in all likelihood 

 in other districts that have not yet been sufficiently sur- 

 veyed. These coals, so far as they have been geologically 

 examined, have been accumulated precisely like the peat- 

 mosses, swamp-growths, and vegetable-drifts of the present 

 day. Some have evidently grown in situ, and accumulated 

 in great thickness and purity for ages ; in others the growth 

 has been interrupted by overflowings of the water, and 

 earthy layers are not unfrequent in the mass; while in 

 others, again, the mass is so irregular in thickness and 

 composition, that it at once recalls the idea of drift and 

 heterogeneous deposition. Whatever the thickness or 

 composition, they are true bituminous coals, thus disprov- 

 ing the belief which was generally entertained some twenty 

 or five-and-twenty years ago, that all true coal was a product 

 of one geological epoch only, and necessarily belonged to 

 the Carboniferous formation. On this point we can offer 

 nothing more convincing than the following extract from 

 Sir Charles LyelTs description of the Eichmond coal-field 

 in Virginia : " These Virginian coal - measures are com- 

 posed of grits, sandstones, and shales, exactly resembling 

 those of Older or primary date in America and Europe, and 

 they rival, or even surpass, the latter in the richness and 

 thickness of the coal-seams. One of these the main 

 seam is in some places from 30 to 40 feet thick, com- 

 posed of pure bituminous coal. On descending a shaft, 

 800 feet deep, in the Blackheath mines in Chesterfield 

 county, I found myself in a chamber more than 40 feet 

 high, caused by the removal of the coal Timber props, 

 of great strength, supported the roof ; but they were seen 

 to bend under the incumbent weights. The coal is like 

 the finest kinds shipped at Newcastle, and when analysed 



