Geological Collections, 



of twelve inches in its middle. This seam of coal is not reputed so good 

 as No. 3. It has been worked, but to no considerable extent, near Berwick. 



5th, The cancer coal is supposed to be from twelve to fifteen fathoms 

 below the stone coal, but the distance between them varies. The seam has 

 not been worked in the eastern part of the district, lying at a considerable 

 depth in that situation; but at Thornton, Shoreswood, Gatherick, and 

 some adjoining places in the western part of the district, it is worked under 

 the name of the main coal. Its thickness is from five to five and a half 

 feet, and its quality is not good, the bed being traversed by thin bands of 

 stone. 



Qth, The three-quarter coal lies at variable distances below the cancer 

 coal, being in some places found at twelve, and at others twenty-two, 

 fathoms deeper than that seam. Its usual thickness is two feet eight inches 

 including a band of stone of ten inches ; its quality is inferior to the better 

 coals of the district. 



1th, The Cowper Eye seam is generally met with about four fathomr 

 below the three-quarter coal ; it varies in thickness from two to three feet 

 of saleable coal, having a stone band in its middle, unequal in thickness, but 

 in some situations exceeding two feet. This seam is chiefly worked in 

 the western part of the district, as at Murton, Thornton, Shoreswood, 

 Felkington, Etal, Gatherick, Greenowalls, and their vicinity. In quality, 

 it is considered equal to No. 3, Scremerstone main coal. 



No. 8. The western coal seam appears to me to be the lowest worked 

 in the district. It has been sunk to at Shoreswood, and there found at about 

 fourteen fathoms below the Cowper Eye seam, but the quality being indiife- 

 rent, it was not thought worth working. At Etal there is a mine carried 

 on in it, though even there the coal is of inferior quality. 



From the gradual rise of the strata to the westward, the first four seams 

 mentioned in the section of the strata near Berwick, do not reach to 

 Thornton, Shoreswood, Felkington, Etal, Gatherick, and Greenowalls. 



Nos. 5, 6, 7, and 8, are the beds worked at those coal mines N. J. Winch 



in Trans. Nat. Hist. Soc. of Northumberland and Newcastle, i. 129. 



Value of Organic Remains in determining the Comparative Age of Forma- 

 tions In the papers, a brief analysis of which I have now placed before 



you, we have some new and striking proofs of the great importance of organic 

 remains in determining the comparative age of remote and discontinuous 

 formations. And we have seen, that in cases where we have few examples 

 of specific agreement, we can, from the aspect of large groups of fossils, and 

 the general resemblance of their generic types, form at least a probable 

 estimate of the age of the deposits to which they are subordinate. Inferences 

 of this kind would be altogether worthless, were they invalidated by the 

 direct evidence of geological sections. But we deny that this is in any 

 respect the case ; and our conclusions are the more certain, because they are 

 not only founded upon a wide induction of particulars, but are consistent 

 among themselves. 



There can be no doubt that, in the ancient ocean, as well as in the present, 

 the distribution of organized beings was affected by many causes — by the 

 temperature and depth of the waters, by the nature of the soundings, by the 

 action of tidal currents, and by other unappreciable disturbing forces. Even 

 among the old secondary groups, we can sometimes separate littoral forma- 

 tions from those of deep seas, not merely by their mineral structure, but 

 also by their fossils ; and, in all geological periods of the history of the 

 earth, formations on the shores, and formations in deep seas, must have gone 

 on together. 



Again, our great formations may be subdivided into many distinct mine- 

 ralogical groups of strata ; and the large suites of organic remains, charac- 

 teristic of the formations as a whole, may also be subdivided into manv 



