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



Another level was brought up from south to norths namely, from the vicinity 

 of the Blackwater into the western part of Dromagh, being about one mile 

 in length. 



The beds thus cut through, show repeated interchanges of dip from south 

 to north, with vertical strata intervening between each change of dip, the 

 coal seams conforming to this arrangement, as illustrated in Section No. 6. 

 Plate I. This section was constructed for the service of Mr. Leader by 

 Mr. Griffith, and for a copy of it, I am indebted to the former gentleman. On 

 the south, the beds dip about 45° to the southward, but in proceeding 

 northward, they gradually become vertical, then incline northward, are again 

 vertical, and afterwards the southerly dip is resumed. This succession is re- 

 peated in the more northern part of the section. It will be seen, that in the 

 line of this level, eighteen small seams of culm were intersected before the 

 four main or bulk beds, and the four other seams north of them, were met 

 with. It will also be observed, that in the northern part of the section, the 

 flexure of one coal bed is perfect in its changeable dip from south to north ; 

 from which consideration, and the general structure of the country, it might 

 be inferred, that many of the coal beds may converge in depth, thus reducing 

 considerably the actual number of the seams. It must be left to future expe- 

 rience, however, to determine, whether these beds are generally continuous in 

 depth. I observed in one part of the field a thin bed of black shale dipping 

 80° north, which in its ascent thinned out, and did not reach the surface ; and 

 a similar discontinuance might occur to a bed in its descent. 



The bulk beds of culm extend in width from two or three feet, to ten, 

 fifteen, and twenty feet, according as the walls are expanded or contracted ; 

 but the bulks occur only at intervals, there being intervening distances void of 

 culm, in which the walls of the bed are drawn nearly close together. These 

 bulks, therefore, are arranged somewhat in the form of parallel pipes, descend- 

 ing into the earth ; and yet in this descent, they are subject to contractions also. 



This level has been extended to the eastward on the main beds, namely, those called the bulk 

 the rock, and the coal veins, about two miles in length, obtaining at the eastern extremity a depth 

 of forty yards below the surface. The workings on coal are conducted above that level, and it is 

 only in a few places, that trials on the coal have been made forty yards deeper, Mr. Leader leaving 

 all below that level, as a reserve for a future period, when, with the aid of deeper shafts and of 

 steam engines, his collieries may be wrought on a more extended scale. 



Faults occasionally traverse the coal-field, ranging north and south, shifting 

 the beds to the north three or four yards, and in some places as much as four- 

 teen or fifteen yards. Of the greater dislocations, three or four parallel ones 

 occur in Dromagh and Gortine. 



In the Dromagh section, it may be seen, that in the great majority of instances. 



