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X. — On the Structure of the Neighbourhood of Gamriey Banffshire, 

 particularly on the Deposit containing Ichthyolites . 



By JOSEPH PRESTWICH, Jun., Esq., F.G.S. 



[Read April 8, 1835.] 



Introductory Remarks. 



The Ichthyolites of Gamrie were first brought before the public by Mr. 

 Murchison, but, having been prevented from inspecting the precise locali- 

 ties, he contented himself with pointing out their existence ; and obtained 

 from Mr. Pentland, an account of their zoological characters*. M. Agassiz, 

 during his recent visit to England, was much struck with the peculiar forms 

 of these Ichthyolites, and expressed his opinion, that they belong to a deposit 

 more recent than that in which the fossil fishes of Caithness are found, and 

 has been shown by Messrs. Sedgwick and Murchison to pass down into strata 

 of the age of the old red sandstone. Impressed with the importance of deter- 

 mining precisely the age of the strata containing the Gamrie fossils, and unable 

 in consequence of other geological researches to do so himself, Mr. Murchi- 

 son, on finding that I was about to visit Scotland, suggested the inquiry which 

 led to this memoir. The result is, that the age of the fish-deposit, as de- 

 termined by the position of the strata, coincides precisely with that suggested 

 by M. Agassiz, from the zoological characters of the Ichthyolitesf . 



These fishes were first discovered in the summer of the year 1826, by 

 Mr. Christie of Banff, and Mr. Dockar of Findon, who, while exploring the 

 bed of a small brook, which flows through a narrow ravine and empties itself 

 into the Bay of Gamrie, observed numerous, flattened, calcareous nodules 

 frequently containing remains of fishes. Tracing these specimens up the 

 brook, they arrived at a thin bed of bluish clay, which inclosed the Ichthyo- 

 lites. 



In my inquiries to ascertain the geological relations of this stratum, I have 

 to acknowledge the attention and civility of the above gentlemen. 



* Geol. Trans., 2n(l Series, vol. ii. p. 363. t ^ee postea, p. 146. 



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