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ME. J. E. MAEE AXD DE. H. A. IS'ICHOLSON 



37. The Stockdale Shaxes. By J. E. Maee, M.A., F.G.S., Fellow 

 of St. Jolin's Coll. Camb., and H. A. Xicholso^^, M.D., D.Sc, 

 P.G.S., Eegius Professor of iS'atural History in the University 

 of Aberdeen. (Eead May 9, 1888.) 



[Plate XYL] 



I. Introduction. 

 II. l^otice of previous writings. 



III. Description of the tj-pical sections of Skelgill and Stockdale. 

 TV. Description of confirmatory Sections. 

 y. Comparison with corresponding Beds in other areas. 

 VI. Eemarks on the bearings of the results. 

 VII. Description of Fossils. 



§ I. liS^TEODTJCTIOlS-. 



We propose, in a series of papers, to supplement the observations 

 which have been previously published upon the divisions, organic 

 remains, and subdivisions of the Lower Palaeozoic Rocks of the 

 Lake-district and adjoining areas. In the investigation of the 

 geological structure of any such complicated region as the Lake-, 

 district, the first step necessarily consists in the determination of 

 those rock-divisions which are developed in the area in question to 

 an extent which renders them capable of representation on the one- 

 inch map of the Ordnance Survey. When the first step has been 

 satisfactorily accomplished, the general structure of the region may 

 be said to be determined ; but there may, nevertheless, remain many 

 points of great geological interest and importance which still require 

 solution. Thus, it is now generally recognized that in any region 

 a set of deposits may have been formed so slowly that a thickness 

 of only a few feet of such may mark a lapse of time represented 

 elsewhere by many hundreds of feet of sediment. In such cases a 

 more minute subdivision of the strata than can be represented upon 

 an ordinary geological map becomes necessary, and it is also essen- 

 tial to enter into a detailed examination and comparison of the 

 organic remains of the different beds. By this method of investi- 

 gation verv important results have already been obtained in other 

 regions, and we see no reason to doubt that the application of the 

 same method to the study of the Palaeozoic Rocks of the Lake- 

 district will result in the eventual filling up of many of the gaps 

 which at present exist in the geological history of this area. 



Under ordinary circumstances it would, no doubt, have been 

 more convenient to commence our investigations with an examina- 

 tion of the oldest rocks of the district, and in selecting the Stock- 

 dale Shales as a starting-point we were iQfluenced by several 

 considerations. In the first place, the Stockdale Shales form a well- 

 marked series, readily separable from the rocks lying below and 

 above them, while they present at the same time considerable varia- 

 tions in the character of their sediments and included fossils. 



