Yorkshire Naturalists at Askrigg. 



213 



constantly slipping- and must have obliterated most of the traces 

 of the old lake levels. Rather strong- evidences of an old 

 strand, about twelve feet above the present water level, were 

 observed, but did not extend very far. The g'orge that had 

 been cut in the drift at the end of the valley was carefully 

 examined, and it was considered that, for the greater part of its 

 leng-th, the drift which forms the steep sides of the gorge has 

 a core of solid rock at no great depth. This conclusion was 

 strengthened by the evidence of springs here and there on the 

 slopes and the narrowness of the valley at Bainbridge, where 

 the drift dies away and the solid rock appears. At this point 

 there were indications of a fault with a small downthrow to the 

 north. Evidently attempts at mining had been made and galena 

 was found on the spoil heap. 



With reference to the larger problem that confronts one, 

 namely, the determination of the sequence and character of the 

 earth movements that produced the differentiation of the Lower 

 Carboniferous rocks north and south of the Craven faults, the 

 great difficulty is the want of reliable data. Despite the number 

 of fossil collectors and their energy in making collections, much 

 of their work is valueless for working out the life zones of the 

 Carboniferous rocks owing to the indefinite way in which their 

 finds are recorded, and to the possibility that the determination 

 of the specific names of many of the fossils may be open to 

 question. In the Bristol area, and also in the Gower Peninsula 

 where the Carboniferous Limestone has received nmch intelligent 

 attention with a view to determining its zonal divisions, the 

 corals seem to be the group that promises the best results. It 

 would seem that the present is the time to make a special effort 

 to investigate the distribution of life in both a vertical and 

 horizontal direction in the Yoredale rocks. The task is simplified 

 in that the alternating limestones, sandstones, and shales form 

 lithological divisions that can be recognised over a large tract of 

 country, while the countless streams have carved the old Car- 

 boniferous plateau in such a way that miles of exposures of the 

 different beds are available, and may be examined. 



It is essential, however, that the exact position from which 

 each fossil is obtained should be recorded, and for that purpose 

 the 6-inch Ordnance Map properly divided and marked may be 

 used and a careful record kept of the work done. The question 

 might be asked : ' What value would such work possess when 

 completed?' The reply is, that the knowledge of a method of 

 correlating the Carboniferous Limestone series north and south 



1905 July I. 



