lyell's travels IN NORTH AMERICA. 393 



The upper, composed of sandstone and shale, with fossil plants.* 



The middle, comprising the productive coal measures. 



The lower, chiefly made up of red sandstone and red marl with 

 subordinate beds of gypsum and limestone. 



Concerning the lower series, which extends to the island of 

 Newfoundland (where, however, the productive coal measures 

 hardly reach), its position was not understood at the time of Mr. 

 Lyell's departure for America; and from the peculiar character of its 

 rocks and the abundance of gypsum it contains, it was supposed to 

 overlie rather than underlie the true carboniferous rocks. Imme- 

 diately after his return to England, our author communicated to 

 the Geological Society his opinion that the whole group was a true 

 lower member of the carboniferous series, and this opinion is fully 

 borne out by the subsequent careful observations of Mr. Dawson 

 already recorded in the pages of this volume {ante, p. 26.), and 

 admitted by Mr. Brown {ibid. p. 23), and Mr. Logan, al- 

 though, according to Dr. Gesner, there is still a want of such 

 evidence as is satisfactory to him. The determination of this 

 point is of very great importance in working out the geology of 

 North-eastern America ; and the similarity now known to exist 

 between some of the fossils from beds above the carboniferous 

 series and those at the very bottom of that series, together with 

 some obscurity in the sections in a very difficult country, render it 

 advisable to quote in this place the heads of the evidence on which 

 Mr. Lyell's conclusions are founded, (vol. ii. p. 204.) 



The first argument offered in the work before us is, that the 

 rocks of what we may safely call the, gypsiferous formation, in 

 Nova Scotia and Prince Edward's Island, always make their ap- 

 pearance nearer to the region occupied by the older rocks, whether 

 Silurian or Metamorphic, and also that they are, on the whole, 

 more disturbed than the coal measures. In attestation of this 

 point, sections are referred to on the East River, and the Minudie, 

 and also near Windsor, the rocks in the latter case being fos- 

 siliferous, and their evidence therefore of greater value. 



In the cliffs near this town, Windsor and in the estuary of the 

 Shubenacadie, these strata are very greatly disturbed and thrown 

 into folds, part of which are tilted at considerable angles, while the 

 rocks are fissured in the direction of their strike and shifted verti- 

 cally. It would appear that there are no indications of the true coal 

 measures having partaken of these disturbances, so that on both 

 these grounds, and also from the probable continuation of the dip 

 observed near the Minudie already referred to, the evidence all 

 points to the same conclusion with regard to the age of the rocks 

 in question. 



The Albion mines near Pictou are remarkable for the great 

 thickness of the coal worked there (estimated at thirteen yards). 

 To the south of this district, Mr. Logan and other geologists have, it 



* These uppermost beds, as they occur in Nova Scotia, are described by- 

 Mr. Dawson in the present number of the Journal. (Se ante, p. 322.) 



