153 



A ■ 



SUPPLEMENTARY, 



OR STRATIGRAFHICAL INDEX 



TO VOL. IV. 



trranging the Shells described therein, accorditig to the 

 several Strata in which they tvere found imbedded, from 

 the newest toivards the oldest in the British Series. 



lioicland Street, April 2lsf, 1823. 

 GENTLE3IEN, 



ON |iiesentiuj; to you a continuation of tliose Stratigraphical Indexes to 

 the Volumes of " Mineral Conchology," wliicli I have been used to pre- 

 pare for my liighly valued and lamented Friend, your late Father, I 

 cannot avoid expressing the great satisfaction I feel at seeing, how well 

 the indefatigable and able Instructions of my departed Friend, and rhe 

 large collection of Specimens and materials which he has left in your 

 ))ossession, is enabling you to continue, to support with credit and 

 increasing usefulness, tlie important work in aid of British Geology, 

 which Mr. Sowerby set on foot, more than ten years before his decease. 



In your youthful energy and love of the subject, and in the zeal and 

 abilities of your many kind Contributors, I see with pleasure an assurance, 

 that "• Mineral Conchology" will continue its progress, until at length, it 

 embraces every species of Slieil, which can in the meantime be found im- 

 bedded, in each one of the Strata of Britain ;— when this shall be accomplish- 

 ed. and the rich stores ofBritish Fossil Shells, thus classified, recorded and 

 rendered fomparable, shall have been compared by the Geologists of other 

 countries, with the shells whicii the Strata thereof may entomb, then, I 

 am of opinion, will Geological truth appear, and the last remains of 

 visionary and wild Theones on the subject, entirely vanish; by Svhich 

 Theories, until Mr. Smith (in 1792) commenced his practical investiga- 

 tions, and mapping of the English Strata, the subject was obscured, and by 

 which, unfortunately, many parts of it are yet disfigured, and the truths 

 of nature concealed. 



7\san instance, Iwillbegto advert here, to the manner in which Writers 

 still cling to the unfounded dogma of an age gone by, wliich asserted, that 

 "our caai-measures exhibit only fresh-zvuter and land productions !" in 

 despite of the evidence, which Shells recorded in your pages, of the 

 several Genera Ammonites, Anomia, Cardita, Conularia, Eunmphalus, 

 Lingulu, Mytilus, Ortlwcera, Fecten, and Tcrebrutida furnish, to the con- 

 trary of such assertion ; which I know to be an unfounded one, from 

 liavingseenfossilShells, of probably four times as many Genera, esteemed 

 marine ones, as are mentioned above, and very numerous Species of 

 many of these, the individuals of which are innumerably scattered 

 tiuough the coal series, in particular districts, in the east of Sutlierland 

 and of Dumfries Counties, in particular: and I believe that such shells 

 are in few Coal-districts wanting, if industriously sought after. 



Rlore than four years ago, on considering the Maps by M. Halloij, and 

 by Messrs. Cuvier and Brongniarl, of the environs of Paris, it occurred to 

 me, that the gypseous and other anomalous Strata, producing BoniiS of 

 Quadrupeds, alleged /resh-w(Uer Shells, Sec. in the vicinity, and south- 

 ward of Paris, are referable to unconfurmabk patches of Strata, of a very 

 vuidcrn era, compared with the strata analogous to the London Clay and 

 Deep- Well series, and the upper and lower Chalk, all o? whose southern 

 edges these anomalous strata locally cover. On considering also, soon aft'.j - 

 wards, the Map and Sections of the Isle of Wight by Mr. Webster, I 

 clearly perceived there, the same unconformablencss (and have often 

 since mentioned the same to my Friends:) and so with regard to the 

 patch of strata, since alleged to coutaiu fresh-ualcr Shells, on and to 

 Jhe^nor Ihwaid of Hoid wcUcliff. 



