SKETCH 



OF THE 



PROGRESS OF GEOLOGY, &c., in 1812. 



We have now brought the labours of our first year to a close, 

 and have recorded every fact of importance elicited during 

 that period in the science of Geology, yet, as these have been 

 distributed in different parts of our publication^ (a natural de- 

 fect of all periodical literature) we purpose in the present in- 

 stance, to recapitulate the principal points of interest deduced 

 from them, in connection. 



Not the least important of these, is the able translation of 

 D'Orbigny's considerations on the Ammonites of the creta- 

 ceous period," kindly forwarded by Mr. Johnson; a depart- 

 ment of the former gentleman's "Paleontologie Fran9aise,'^ to 

 which the president of the Geological Society of London* 

 alluded generally in such marked terms of approval at the 

 last anniversary of that body, whilst, in particular, he states 

 that the considerations on the Ammonites have led him to con- 

 clusions of the highest interest, both zoological and geologi- 

 cal. In the former respect, his observations on the external 

 character of Ammonites, and on the limits of their natural 

 and accidental varieties, of the differences of sex, and particu- 

 larly of age, are entirely original. The previous labours of Geo- 

 logists had contributed to a general knowledge of those of the 

 northern chalk and green sand, whilst the southern tribe was 

 unexplored until recently, and the labours of M. D'Orbigny 

 therein, have proved the successive faunas of the great cre- 

 taceous formation of France, and their distinctness from those 



* Proceedings Geological Soc. of London, Vol. III., No 86, p. 668. 



