1822.} Mr. Winch’s Reply to Messrs. Young and Bird. 309 
been quite sufficient indications to ground a venture on. Near 
the debris of this mine the hornblende and epidote may be found 
crystallized more distinctly, and the dark-green mica aggregated 
in larger and more characteristic masses than is usual. The 
latter (the mica) is of that variety which occasionally scratches 
glass. It fuses readily before the blowpipe into a greenish-black 
glass. The disintegrating variety (Cat Dirt) is more difficult of 
fusion, and the result more slaggy. I may add that the quarries 
of Ledbury have of late produced many specimens of a trilobite 
nearly resembling that of the South Welch transition rocks of 
Dynevawr and Built, and that calcareous spar of a very pure 
rose colour is found in large laminz interposed between the strata 
of limestone. I could not find it crystallized. If it occurs in 
that state, it must form specimens of singular beauty. 
Believe me, dear Sir, very truly yours, 
J.J. CONYBEARE, 
ARTICLE IV. 
Reply to Messrs. Young and Bird. By N.J. Winch, Esq. 
(To the Editor of the Annals of Philosophy.) 
SIR, Newcastle-upon-Tyne, Oct. 7, 1822, 
However unwilling I may be to occupy your pages with 
controversy, yet as an honorary member of the Geological 
Society of London, I consider it a duty I owe to that body not 
to allow the misrepresentations of the Rev. Mr. Young and Mr. 
Bird, of Whitby, printed in your last number, to stand on record 
unanswered, particularly as the Society is mentioned in their 
letter. The hills and a portion of the flat country in the north- 
east of Yorkshire are now ascertained to belong to the lias 
formation; the upper beds consist of sandstone, shale, and 
limestone, with thin seams of coal, the lower bed of shale or alum 
slate, but the limestone and coal are not interstratified with the 
other beds throughout the whole district, and in many places the 
alum shale bassets out, or possesses a very thin covering, my 
criltes’ ‘ideas of geology being formed only from the inspection of 
a very limited disirict.” (See Introduction to Conybeare and 
Phillips’s Outlines of Geology, p. xiv.) They have considered 
the upper strata and lower stratum as distinct formations, and 
upon this assumption the whole of their statements rest. On 
such false premises they attempt to convict me of what the 
term gross mistakes, but let my account of the outline of the 
lias be compared with Mr. Greenough’s map, and the discre- 
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