56 Mr. Weaver on the Geological Relations of the South of Ireland. 



velopedj in passing from the western declivity of Derrybryan mountain through 

 Gort (§. 69), across the plains to the limestone hills on the west, which there 

 form the bounding line between Galway and Clare. Near Kilmacduagh 

 Abbey and Rockfield, a few miles west of Gort, are broad sheets of bare 

 limestone rock, extending repeatedly over many acres, and separated from 

 each other, only by small green patches of herbage or pools of water. 

 The eye thus ranges over large fields of naked rock in nearly hori- 

 zontal strata, but fissured at the surface into quadrangular masses. This 

 desolate scene is continued to the limestone hills on the west, where the 

 same horizontal arrangement prevails, as may be noticed in their escarp- 

 ments, which being in many places divested of all vegetation, the eye traces 

 with facility the corresponding strata from hill to hill. In the projecting 

 and partially isolated hills, this disposition is very striking, as in those 

 adjacent to Glancolmkill, where terraces of horizontal strata, receding one 

 above another, present the stair-like form, so characteristic of many trap 

 districts. 



The Clare limestone is distinguished by the general continuity of its strata. The organic re- 

 mains which have incidentally appeared to me, correspond generally with those derived from other 

 portions of our field. I have already adverted (§. 57.) to the fossils noticed adjacent to the Shannon 

 by Messrs. Weller, Sheppard, and Wright ; and I shall merely add, that in the limestone of the 

 peninsula of Renville, on the south side of the bay of Galway, I met with two species of Pen- 

 tremites, which appear to be undescribed. 



Coal Formation. 



(71.) This formation in Clare, as in other parts of Ireland, forms hills of 

 greater or less magnitude, planted upon the carboniferous limestone in con- 

 formable position ; the latter being at the foot of, or rising only a certain di- 

 stance up, the escarpment on its northern and eastern sides. 



Viewed on the large scale, the entire coal-field may be described as 

 a nearly uniform plane, corresponding to that of the subjacent limestone, 

 the angle of inclination seldom deviating more than a few degrees from the 

 horizon, and the prevailing dip being from the east of north to the west of 

 south. The highest portion of this area is the district of Mount Callan, which 

 rising some hundred feet above the general level of that part of the coal coun- 

 try which is situated further north, is still more elevated above the southern 

 portion of the tract; the surface of the latter gradually declining in that di- 

 rection nearly to the level of the sea. In the higher grounds, however, as well 

 as in the southern, or lower parts of the field, the coal measures may be oc- 

 casionally observed, disposed in a gently undulated form. 



The general arrangement thus described, may be traced along the eastern 



