Stratigraphical Gcoloi^v. 89 



Belfast. The clay rests upon intensely glaciated rocks; the 

 Cretaceous rocks of Antrim and the Ordovician shales of 

 County Down retain the polishing and scoring in great 

 perfection. The division into upper and lower boulder clay, 

 with the intermediate sands and gravels, is not always 

 apparent ; often only one division being visible. The clay 

 is typically red, tough, unstratified, and laden with erratics 

 well rounded and scored, of all dimensions, from great 

 blocks of chalk and basalt down to tiny pebbks, which 

 have often travelled long distances from their parent 

 locality. 



In different districts the texture varies consideral:)ly, some 

 clays containing a good deal of sand, probably derived from 

 the Trias. Interesting deposits of stratified sands and gravels 

 are numerous in the Dundonald valley in County Down; 

 even more extensive deposits are to be found at Antrim, 

 Killagan, and the Carey river valley in the County 

 Antrim. The study of boulder clay and erratic blocks 

 has occupied the attention of members of the Belfast 

 Naturalists' Field Club for a considerable period, and 

 the footnote gives references to their publications on the 

 subject. 



Scotch erratics are fairly common in our drift ; the frag- 

 ments of riebeckite eurite from Ailsa Craig (?) are almost 

 ubiquitous. Many igneous rocks of Antrim are easily 

 identified, and have furnished valuable evidence of the 

 direction of ice-flow, generally from N.E. to S.W. 



Some of the erratics from Antrim are of considerable size, 

 such as the " Butterlump " Rock, on the shores of Strang- 

 ford Lough. Shells occur occasionally in our glacial 

 deposits and usually in broken fragments, except in a few 

 places, such as Woodburn, where the valves of the delicate 

 Leda were found still in juxtaposition. Foraminifera and 



S. A. Stkwart, f. R..S. e. — The Mollusca of the Boulder Clay of the 

 North-east of Ireland. Appendix to j^nv. H. N.F.C. , 1879-80. 



Josi'KH Wright, k.c.s. — Post-Tertiary Foraminifera of the North-east 

 of Ireland. Appendix to /-"/ft". B.N.F.C., 1879-90. 



Miss S. M. THOMi>sf)N. — Report of the Geological Committee. Proc. 

 B.N.F.C. , 1893-94. I/yid. 1894-95, 1895-96, etc. 



R. Ll. Praegek. — Bibliography of Irish Glacial and Post-Glacial 

 Geology. Appendix to /"/'tit:. B.N.F.C, 1895-96. 



