590 



That from the Foreland sandstones (1) on the north to the 

 Trilobite slates (6) on the south inclusive, the angle of dip increases 

 from 20" to 80", being 20" to 30° in the Foreland sandstones (1) and 

 Linton calcareous slates (2), 45" to 70° in the Trentishoe quartzy 

 slates and sandstone (3), 70" to 80" in the Morte slates (4) and 

 Wollacomb sandstones (5), and generally in the Trilobite slates (6), 

 though in the last a lower angle is sometimes observable on approach- 

 ing an undulation. The general strike of the beds is from 10" to 15" 

 N. of W. and S. of E. from a true meridian. 



That on the other hand the Wavellite schistus, limestone, and 

 shale (7) and culmiferous beds (8) undulate on a very large scale, 

 and are occasionally subject to contortions upon a smaller. 



From the Foreland sandstones (1) to the Trilobite slates (6) in- 

 clusive, the series is connected throughout, passing from one to the 

 other in such a manner as to form a consistent whole, the parts of 

 which cannot be separated one from another without arbitrary divi- 

 sions. 



Though the beds, from 1 to 6 inclusive, form one consistent, 

 consecutive series, yet the subordinate parts are subject to change in 

 different portions of the field, both mineralogically and in extent, 

 and occasionally thin out, as in the case of the beds of limestone. 



On the other hand, the Wavellite schistus and limestone (7} 

 and culmiferous shales (8), though apparently in some places in a 

 parallel (conformable) position with the Trilobite slates (6), do, 

 when thoroughly examined upon the line of outcrop in the district, 

 form a break vdth number 6, and are unconformable thereto. 



That this unconformity denotes two different seras of deposition, 

 an inference supported by the difference in the organic remains ; and 

 Mr. Weaver further states, that he does not consider the occurrence 

 of a few coal plants in the Wollacomb sandstones (5) as at all inter- 

 fering with this inference. 



That the preceding data justify the conclusion, that the strata 

 from 1 to 6 belong to a system distinct from that which includes the 

 beds 7 and 8, the former constituting a peculiar transition group ; and 

 the latter belonging to the true coal measures of England, the old 

 red sandstone being alone wanting. 



In conclusion the author dwells upon the importance of attending 

 to mineral composition in surveying extensive systems of rocks ; but 

 he adds, that " the only safe guide in researcheb into the crust of the 

 earth, is to keep constantly united in view, relative position, organic 

 remains, and mineralogical characters ; and not to restrict our at- 

 tention to one of these distinctions when judging of geological form-: 

 ations." 



