ANNIVERSARY ADDRESS OF THE PRESIDENT. 173 



we, as geologists, have to thank that provincial Government for 

 commencing so useful an undertaking, we have also the satisfaction 

 of feeling convinced that it will be prosecuted with vigour by the 

 present Governor, Earl Cathcart, one of our own body, and, as 

 we know, an able and active geologist. This is a section of the 

 same series of coal-measures so carefully examined and described by 

 Mr. Lyell*, though with less minuteness of detail as to the lithological 

 characters and dimensions of the several beds. The phaenomena 

 exhibited in the above sections are not peculiar to them ; they are 

 to a great extent common to all coal-fields, particularly in the 

 higher parts of the carboniferous series. 



Before giving the analyses I have made of these sections, I wish 

 to call to your recollection that in both theories it is assumed, that 

 the deposition of the coal-measures took place in the sea. Mr. Lyell 

 speaks of the accumulations having taken place in a sea : he says, 

 " It by no means follows that a sea four or five miles deep was filled 

 up with sand and sediment ; on the contrary, repeated subsidences 

 may have enabled this enormous accumulation of strata to have taken 

 place in a sea of moderate depth." ''^;^ 



The example from South Wales is a vertical section f, representing 

 the beds as they are known to succeed each other in descending 

 order, the dimensions being the thickness of each bed at right angles 

 to the plane of stratification. The coal-measures rest upon carboni- 

 ferous limestone, in an inclined and somewhat waved stratification ; 

 and although these measurements would vary in different places, 

 from the swellings and thinnings-out which all strata exhibit more or 

 less when traced to a distance, they are probably not far from the 

 average amount over a large area. 



1. From the top of the highest bed to the limestone, the sum of the 

 measurements amounts to nearly 7000 feet ; that is, the beds must have 

 been originally deposited over each other in horizontal or nearly horizontal 

 stratification to that thickness. 



2. Reckoning only the greater divisions, when a difference of mineral 

 character takes place, there are, besides the coal-seams, 340 beds, from a 

 few inches to 190 feet thick, without alteration of mineral composition; 

 involving, in the latter cases, long periods without any change in the nature 

 of the detritus washed into the water where the deposition was going on. 



3. These beds consist of sandstones, arenaceous and argilliferous slates, 

 and clays, alternating without any apparent order of succession ; some- 

 times one sometimes another lying upon the coal ; and occasionally^ but 

 not frequently, the shale upon the coal is said to be carbonaceous. 



4. Interstratified with these beds are eighty -four seams of coal, from 

 one inch to nine feet thick ; the highest being covered by a series of beds 

 of sandstone, &c. 200 feet thick ; the lowest seam separated from the car- 

 boniferous limestone by 1340 feet of similar sandstones and shales, making 

 the coal-hearing strata 5460 feet in thickness. 



5. The seams of coal occur at very unequal distances ; some are sepa- 

 rated by a few inches only of shale or sandstone, others by as much as 

 360 feet. 



* ' Travels in America,' vol. ii. p. 178. 



t No. 1 in the series, illustrating the horizontal section No. 7. 



