Sandstone does not invariahly cover Slate. 281 



Mr. Jameson has noticed this remarkable Rock, in his Survey 

 of this County, unless we admit him to have classed it as neivest 

 JJceiz (although underlieing what he calls the Independtnt Coal' 

 formation !) : it is true, in p. 79, he tells us, what members Wer- 

 ner savs this latter formation consists of, and this Rock having 

 no place there, it may from this circumstance have been over- 

 looked : — an ideal and a real thing, will not always correspond ex- 

 actly: and theory, we have been told, sometimes blinds observers. 



1 do not pretend to say, that Sandstone is never found in the 

 situation mentioned by Dr. G. because he will find in pp. 126 

 and 326 of vol. xliii. that 1 observed, very variably coarse and 

 conglomerate Gritstone upon the coarse Slate, on most of the 

 western side of the Anglesea Coal-basin ; but it is ])roper I 

 should add, that in the southern part of its eastern side, no such 

 rock was visible, but in its place, a basaltic kind of rock, very 

 similar to that of Dumfries-shire which I have mentioned, but 

 nearer perhaps approaching to slate. 1 saw also a great deal of 

 variably coarse Gritstone, basseting from under the Limestone in 

 the great Forest of Brecon, p. 125, of vol. xliii. 



The very probable errors of Mr .W. Forster and of Mr. Bakewell's 

 Section*!, in placing red sandstone under the metalliferous Lim.e- 

 stone of Cross Fell, have been pointed out, in the note on j). 172 

 of your last volume; and in p. 458 of the Appendix to Mr. Bake- 

 well's Geology, 2d Edition (subsequently printed) the justice of 

 this remark seems admitted: and Mr. B. here and pages 369, 

 397, &c. concurs with me in saying, that sowefimes only, sand- 

 stone is found in this situation, and not generally, as Dr. G. 

 wishes to persuade. 



It seems, however, extraordinary, that Dr. G., after generally 

 assuming, that red sandstone is to be found under the English 

 mountain Limestone, should in pages 1S5 and 1&7, fs peremp- 

 tnriiv infer, that it is not to he fonnd under that of the Low Peak 

 Hnndred of Derbyshire and the adjacent parts of Staffordshire, 

 in ttii". absence o/ all prooJ\ for or against his latter assumption ; 

 as he might have learned, from my Report i. 280, 297, and 478, 

 Phil. Trans. 1811, or P. M. vol.'xxxix. p. 29, &c. In the de- 

 tailed account of the Derbyshire Strata, which underwent in 

 1813, tlie Gcognostic ordeal and suppression, already mentioned, 

 I suggested, and endeavomcd to enforce the us2 and propriety, 

 of a boreing (with Ryan's trepan Auger) being made, in the most 

 deeply excavated part of the 4th Limestone Rock, for correctly 

 a-scertaining the facts of its under strata. Qiare, would not a 

 great majority of tliesuliscribcrs to the Society alluded to, better 

 approve the appropriation of a part of its Funds to such a pur- 

 pose, than to the unnecessary (not to say the piratical) copying 

 and engraving of other persons' Maps?, 



In 



