236 Kendall: The Concealed Coalfields of YorJzshiye, etc. 



Aclose analysis of. the details of boring's through theSecondary 

 rocks reveals no tendency in them to thin out or disappear by 

 unconformity in approaching this line ; on the" contrary, such 

 evidence as is obtainable points to the directly opposite opinion, 

 the Secondary rocks seem to swell out in that direction. 



This, however, is not decisive— the Wealden anticline in the 

 south of England and the Cleveland anticline in the north are 

 both folds affecting the Chalk, and both appear to be reared 

 upon pre-Permian folds (the Cleveland arch certainly is), yet 

 both regions are areas in which Jurassic and Cretaceous rocks 

 attained an immense development. 



This testimony seems quite indecisive, but there are two 

 facts which induce me to believe that the Willoughby anticline 

 is the true boundary of the coalfield. The Coal Measures up to 

 the eastern edge of the visible field are persistently dipping 

 eastward, the boring- at Haxey (South Car) shows, however, 

 that not only is the thickness of Coal Measures above the 

 Barnsley Bed less than it is in the pits on the same parallel 

 further west, but also that the strata are 'absolutely flat,' or, in 

 other words, are rising eastward relatively to the Permian rocks 

 which cover them. 



This may be quite a local arrangement, but, if not, it proves 

 that Haxey lies to the eastward of the axis of the trough in 

 which the Coal Measures lie. Further corroboration is furnished 

 by the magnetic survey of Messrs. Thorpe and Riicker, which 

 indicates a belt of high magnetic deviation coinciding closely 

 with the direction of the Willoughby anticline. None of the 

 evidence can be regarded as convincing if taken by itself, but 

 I think that there is some cumulative value in the three distinct 

 classes of testimony. 



The chief practical importance of the demonstration is this : 

 If the fold is a posthumous one, mining operations would cease 

 in an easterly direction in consequence of the rising of the Coal 

 Measures against an axis of older rocks, while if it be not a 

 posthumous fold mining would cease at about the same line by 

 the descent of the Measures below the limit (4000 feet) at which 

 coal-working would be practicable or profitable. The question 

 may perhaps find a decisive answer from a boring which is now 

 being put down at South Cockerington, near Louth. 



I should have preferred a site west of the anticline rather 

 than east of it as more likely on any hypothesis to meet coal at 

 a moderate depth ; all the same it is a bold and apparently well- 

 directed attempt deserving of success. 



Naturalist, 



