Mr. Bryce on a Tertiarj/ Deposit near Belfast. 433 



Forbes included, in his views, the sliding of glaciers by melting, 

 that I did so, on the same ground on which Mr. Hopkins denies 

 that De Saussure regarded a glacier as a rigid mass ; namely, 

 that to suppose otherwise, would be to attribute an absurdity 

 to a distinguished and philosophical traveller. With regard 

 to Mr. Hopkins's assertion, that we may as justly include in 

 De Saussure's theory the true part of Prof. Forbes's, as in 

 Prof. Forbes's the true part of De Saussure's, I suggest, that 

 Prof. Forbes wrote sixty years later than De Saussure, and 

 had read and carefully studied De Saussure's writings; and 

 that this makes a great difference in the chance of one having 

 adopted the true part of the other's theory. Prof. Forbes's 

 theory includes what was true in that of De Saussure, in the 

 same way that Copernicus's theory included what was true in 

 that of Ptolemy. Mr. Hopkins has used the word " appro- 

 priation " in reference to this subject; but nothing has been 

 said which is any excuse for the introduction of such a term. 



I am, dear Sir, 

 Your faithful and obedient Servant, 



Trinity College, Cambridge, W. Whewell. 



April 12, 1845. 



LXI. Notice of a Tertiary Deposit lately discovered in the 

 neighbourhood of Belfast. By James Bryce, Jun., M.A.^ 

 F.G.S. 



T N the winter of 184-2-43, a shelly deposit was discovered at 

 -■- Belfast in excavating the lower basin for the new water- 

 works. A short notice of it, drawn up by Mr. Hyndman and 

 myself, with a list of the shells, was at Captain Portlock's 

 request furnished to him for insertion in the appendix to his 

 Report on the Geology of Londonderry, Tyrone and Fer- 

 managh, then passing through the press. In the cuttings for 

 the Cavehill railroad, made within the last few months, the 

 deposit was again exposed through a considerable space, and 

 in a direction somewhat transverse to the former cuttings, by 

 which some new facts and additional species liave been dis- 

 covered. 



The deposit is situated about one mile north of the town, 

 at the height of 106 feet above low water in the bay, and 

 consists in the lower part of a very tenacious compact gravelly 

 clay, of a bluish-gray colour, from eight to twelve feet thick; 

 and in the upper part of stratified red sand and red clay five 

 or six feet thick; above this is a thick recent alluvium. The 

 lower blue clay rests immediately on the gypseous marls of 

 the new red sandstone, and is the chief repository of the shells, 



PhiL Mag, S. 3. Vol. 26. No. 1 74. May 1 845. 2 G 



