606 Scientific Proceedings, Royal Dublin Society. 



The Ordoyician grits are very little used even for local pur- 

 poses, the associated slates being preferred for ordinary work. At 

 Strabane, Oastlederg, and other places in the north of the county 

 the metamorphosed Ordovicians [Micalyte, Argillyte, &c.) are used 

 for walling, the cut-stone work nearly invariably being Carboni- 

 ferous Sandstone. Near Strabane flags are procured. 



Silurian. — These range from conglomerate to fine sandstones ; 

 in general being silicious, but often argillaceous, or even carbona- 

 ceous. Similarly, as in the Co. Fermanagh, they have been used a 

 little for cut-stone purposes, and are very suitable for coarse work, 

 such as bridges and walls. Formerly, in some places, the very 

 silicious varieties were wrought into millstones. 



Lacagh. About two miles south-east of Fintona. — Purple and 

 reddish ; conglomeritic ; yields sills and quoins ; used in the build- 

 ing of Fintona new bridge. 



Dungoran. Near Fintona. — Yellowish ; grains white quartz ; 

 a little argillo-silicious cement. 



Raveagh. Near Fintona. — Brown ; makes good rubble ; used 

 in Raveagh House. 



Dundiven. Three miles south-west of Fintona. — Cream colour, 

 greyish-white, and greenish-grey. Rather argillaceous and fel- 

 spathic ; partly calcareous ; granular ; fine-grained ; free- working. 



Lackagh. Three miles from Fintona. — Dark-purplish; semi- 

 crystalline. 



Pomeroy. A mile from. — Dark-purplish grey ; semi-crystal- 

 line ; granular ; micaceous ; works fairly well. 



Lower Carboniferous Sandstone. — Generally greyish or yel- 

 lowish in colour ; some, however, reddish ; more or less silicious ; 

 unequal grained ; works freely, but soon wears the tools. In 

 places some of the more silicious varieties were wrought into mill- 

 stones. 



Devrynascope. One mile from Augher. — Greyish and yellow ; 

 silicious-grained, with, in some beds, a reddish felspathic cement. 



Dernasill. Four miles from Augher. — Greyish-white to yel- 

 lowish; silicious; argillo-silicious cement ; granular; micaceous; 

 in some beds ferriferous. 



Altaven. Five miles from Augher. — Greenish-white, with 

 yellow seams ; very quartzose ; unequally grained. 



Ballymagoivan. One mile from Clogher. — Yellowish ; white 



