50 On certain Points connected with 



as sufficiently rich in itself to aiford ample compensation to 

 the most unwearied investigation. lam induced to trouble 

 you with this letter, in consequence of a call made on your 

 readers bv Mr. John Farey, in your Number for February, 

 for inlormaiion on some particular points connected with 

 the siiper-posiiion of the strata, as well as from some re- 

 marks said to have been made on a similar subject By Mr. 

 Robert Bakewell in your Number for March. 



Mr. Farey, I am afraid, must have mislaid his notes, made 

 along with me in the Forest of Dean eighteen months ago, 

 when I detailed to him the regular succession of the upper coal 

 series from the upper red down to the yellow lime ; at the 

 same time offering to show him in several places the yellow 

 limestone emerging from under its massy incuiTibent, as- 

 sx)cialcd in situations where the thickness of the covering 

 stratum could have been nearly ascertained, or even sub- 

 jected to accurate measurement. Mr. Farey however says, 

 in page 103, that he has never been able, satisfactorily, to 

 ascertain which was the incumbent njeasure or stratum to 

 the yellow, or, as it has been termed by some since the 

 able analysis of Mr, Smithson Tennant, the magnesian 

 lime. In an arrangement I have made for my own use, I 

 term it the second limestone, reckoning upwards and be- 

 ginning with the Derbyshire series. 



It may be proper to observe, that I conceive the super- 

 stratum to the yellow lime to be that which is denominated 

 .by Jameson the old red formation, and in my arrangement, 

 the great red, in contradistinction particularly to the marly 

 red, which surmounts the upper coal series. The thickness 

 of this stratum is variable. Where its immense beds are 

 allowed without the intervention of faults or waves to stretch 

 themselves out in regular succession, 1 have not estimated 

 it at less than l600 yards, and in some places, particularly 

 from the hi^h grounds to the south of Ross in Hereford- 

 shire to its termination or regular ending at Berristone Hill 

 between Ross ard Ledbury, not less than '2000 yards. 



This vast stratum is composed of alternations of parti- 

 coloured stone, in which the red colour predominates; 

 breccia, regularly stratified clay, clav more iriable and in a 

 marly state. The joints of the rocks afl'ord gypsum. The 

 beds of clay, rock salt, or salt sprmgs, as at Droitwich, 

 Nantwich, ic. : the marl, sometimes stratified gypsum. It 

 appears to me extremely probable, that the gypsum pits de- 

 scribed by Mr. Farey, page 104, had been worked in a lower 

 bed of the great red, and immediately over the yellow lime. 

 This, however, ought not to be admitted as proof, unless 



the 



