Kinahan — On Irish Arenaceous Rocks. 599 



of these, when of limestone-gravel, are excellent as manure, others 

 of a different character are not. River sand also occurs very 

 generally. 



SLIGO, 



In the little promontory (Bosses) between Drumcliff and 

 Sligo Bays is a small outlier composed of metamorphic rocks ; 

 while coming in from Mayo, near the centre of the west mearing, 

 and extending north-east across the county, is a portion of the Ox 

 Mountain range. These hills, as has already been mentioned, have 

 a nucleus of metamorphic rocks, which are probably the equi- 

 valents of the Arenig, or possibly of the Cambrian ("Introduc- 

 tion," page 515 ; Mayo, page 587), and margining them in places 

 are Lower Carboniferous Sandstones. To the extreme south, in a 

 small portion of the Curlew Mountains, there are Silurians of the 

 " Old Bed Sandstone" type, coming in from the neighbouring 

 counties, Mayo and' Boscommon, which are margined to the south- 

 ward by Lower Carboniferous Sandstones. To the east of the county 

 are Coal-measures, a small portion of the Connaught Coal-field ; 

 while to the westward of the main mass are small outliers, lying 

 oast and west of Lough Arrow. In recent times sandstone has 

 not been much used in this county for cut-stone purposes, as in 

 general limestone is preferred. 



Cambrians (?), Arenig, and Ordovician. — The rocks that 

 probably are the equivalents of those of these groups are all more 

 or less metamorphosed. There are, however, in them some quartz- 

 rock and quartzyte, suited for heavy rough work and for road 

 metal. 



Silurian. — In the small area included in this county the rocks 

 are similar to those adjoining, in the Co. Boscommon. They are 

 of inferior quality for cut-stone purposes, being generally coarse 

 and hard or argillaceous. They are, however, in places locally 

 used. 



Carboniferous. Lower Carboniferous Sandstone. — Some of the 

 beds near Lough Gara, on the south slopes of the Curlew Moun- 

 tains, are very similar to the rocks utilized at Boyle, in the Co. 

 Boscommon ; but here they do not seem to have been worked. 



Westward of Ballysodare Bay and the neighbourhood of 



