4-34- Mr. Bryce on a Tertiary Deposit lately discovered 



a few only being found in the upper sand and clay. The 

 shells are in every state of preservation : some are rolled and 

 polished ; some, though strong shells, are broken into frag- 

 ments, while others, though of a fragile nature, are in a state 

 of perfect preservation. The same observation has been made 

 by Captain Portlock respecting the tertiary clays of Lon- 

 donderry (Report, chap, vi.) ; and he points out the con- 

 clusion to be drawn from it respecting the origin of these 

 beds. 



There have been identified in all forty-five species of shells, 

 and there are fragments which may belong to others. From 

 the occurrence oi' Nucula ohlonga, which is now extinct, and 

 found fossil in the crag and Sicilian pliocene beds, and of 

 Fusiis contrarius^ also a crag fossil, and of which no living 

 locality is known, the deposit was assigned by us to the newer 

 pliocene epoch. In this view we were supported by Captain 

 Portlock, who, prior to the discovery of the Belfast deposit, 

 had assigned the same age to certain calcareous clays and 

 gravels in Londonderry. These contain, however, a very 

 limited number of species in comparison to those which occur 

 with us. They extend inland about fifteen miles, and in ele- 

 vation far surpass our deposits, ranging fi-om near the sea- 

 level to between 400 and 500 feet; yet they were found to 

 contain but three species, Nucida oblonga, Turrit ella terehra 

 and Cyprina Islandica^ all of which occur also in the Belfast 

 beds. In an excellent paper by Mr. Oldham on the state of 

 our knowledge of these deposits in Ireland, an abstract of 

 which was published last year in the Proceedings of the Geo- 

 logical Society of Dublin (vol. iii. part L p. 61), only sixteen 

 species are enumerated as the result of his own researches, 

 and those of Dr. Scouler and others in various parts of the 

 country. The Belfast deposit alone thus contains about three 

 times the number of species yet described as occurring in Ire- 

 land. This is, I suppose, to be explained less by any original 

 difference in the conditions under which this deposit took 

 place, than by the watchfulness of various collectors during 

 the removal of the great quantity of matter, about 10,000 

 cubic yards, which was taken from these beds alone. 



In the lower clay, in which the shells chiefly occur, rounded 

 fragments of almost all the primary and secondary rocks of 

 this country are found with many fossils of the latter class. 

 The adjoining mountains, which are composed of the upper 

 secondary and trap rocks, afford an obvious origin for some 

 of the pebbles; for the others a more distant origin must be 

 sought. The Mourne range is excluded, as containing but 

 very few of these. They may have been transported from 



