1821.] . Mr. Weaver on Floetz Formations. 245 



No. 21 in Mr. Greenough's Geol. Map), several seams of good 

 coal, varying from a few inches to three feet nine inches in thick- 

 ness, are found in direct alternation with the sandstone, lime- 

 stone, and slate-clay. 



General Remarks. — In the first floetz series of England and 

 Ireland, trap, porphyry, or amygdaloid, are occasionally found ; 

 not only in separate association with the old red sandstone, with 

 the limestone, and with the coal formation, but conjointly with 

 all the three together. Separately: in the old red sandstone 

 formation in Mellfell, Cumberland (Group, No. 22, with trap, No. 

 34, of G. M.) ; in the limestone formation in the county of Lime- 

 rick, and in Derbyshire (Groups, No. 21 and 20, with trap, No. 

 33 and 32, of G. M.) ; and in the coal formation in Staffordshire 

 (Group, No. 18, with trap, No. 31, of G. M.)* Conjointly, in 

 alternation with the sandstone, limestone, slate-clay, and 'coal,, 

 in Northumberland (Group, No. 21, with trap, No. 33, of G. M.). 



5. Scotland. — The intimate connection of the old red sand- 

 stone with trap, porphyry, amygdaloid, limestone, slate-clay, and 

 coal, is also very striking in Scotland, all being found in that 

 country in repeated alternation with each other, and presenting 

 no very determinate order of succession, save that the lowest 

 portion of the old sandstone formation constitutes in general the 

 great foundation of the whole series. Dr. Boue, in his highly 

 valuable work,+ observes, that the tracts of the old red sandstone 

 in that kingdom containing coal may be conveniently divided 

 into a loiver and an upper portion ; the coal in the former appear- 

 ing in inconsiderable beds, as pitch-coal, or occurring in the 

 form of a black powder mixed with earthy particles, or as beds 

 of anthracite, which are sometimes of greater thickness. But it 

 is in the upper portion of the series that the true workable coal- 

 fields, which form the great object of the miner, are chiefly 

 found ; and in this portion, certain quarters are distinguished by 

 the absence of beds of limestone, by the abundance of coal and 

 vegetable impressions, and by freshwater shells 5 circumstances, 

 which are characteristic of the great coal fields of England, but 

 which are of rare occurrence in Scotland. Of the general struc- 

 ture now noticed, as prevailing in the latter kingdom, Dr. Boue 

 has given a clear exposition in the body of his work, beside 

 detailed descriptions of very instructive sections in the notes 

 appended to it. 



General Remarks. — As in the tracts of the first floetz series, to 

 which my preceding observations have been directed, the forma- 

 tions composing them correspond in general geological relations ; 

 so also they partake of similar mineralogical characters, and are 

 distinguished more or less by the same organic remains. 



The old red sandstone, wherever it comes in contact in those 



• Sec also Mr. Aikin's paper in vol. iii. of the Geol. Trans. 



t Kauai Geologiquc sur l'Kcosse, par A. Boue, MD. ; an instructive and compen- 

 dious view of the geological structure of Scotland. 



