412 T. V. Holmes— The Whitehaven Sandstone. 



a bed in the uppermost strata. That the unconformity has not been 

 noted, only adds to the strong presumption that there is none to 

 note, and that instead of increasing in magnitude from Whitehaven 

 north-eastward to Shalk Beck it does just the reverse. 



Indeed, it is time that we recognized that the magnitude of this 

 unconformity, so certain to be noted by all geologists because con- 

 spicuous in a sea-cliff and accompanied by a change of colour, in 

 a country where natural sections are so few, may have been 

 immensely exaggerated. The Cumberland Coalfield is small and 

 drift-covered, and it is impossible from observations in the field to 

 learn much about the characteristics of its various beds. Even the 

 railway cuttings generally show nothing but Glacial Drift. But if 

 we turn to the Geological Survey Memoir on the Yorkshire Coal- 

 field, a district practically free from Glacial Drift, we learn from 

 Prof. Green's remarks in chap, ii much which illustrates the fact 

 that the circumstances under which the Coal-measures were deposited 

 were such as frequently to produce appearances of unconformity 

 which are really mere local erosions. He notices, p. 14, that the 

 sandstones are great wedge-shaped banks which sometimes, from 

 a thickness of 100 ft., wedge out to nothing in a space of half a mile 

 or less ; that they are equally inconstant in composition or grain, 

 a coarse, irregulaidy-bedded grit passing into a fine-grained, laminated 

 sandstone, etc. ; and remarks that these facts are easily explained 

 if we suppose the sandstones " to have been deposited on an uneven 

 floor, in shallow water traversed by numerous and opposing currents. 

 Their wedge-shaped form may be sometimes due to their being 

 banks piled up by currents running now from one and now from 

 the opposite quarter, and may be sometimes caused by depressions 

 in the bottom of the water having been filled in with sand." 



Then we read on p. 24 — " The junction of a sandstone with the 

 overlying shale is often very uneven, as if part of the original sand- 

 bank had been cut away before the sand began to be deposited. In 

 many cases, too, the top of a sandstone is furrowed by branching 

 channels, such as would be cut out by a system of little rivulets. 

 In such a case there can be little doubt that the surface of the 

 sandstone bed was for a time a land surface traversed by streams of 

 running water." 



The general conditions under which the Coal-measures of West 

 Cumberland were deposited were evidently identical with those 

 prevailing during the Coal-measure period in Yorkshire, and would 

 tend to produce similar results in each district. It seems, therefore, 

 useful to remind those interested in this question both that the 

 lithological character of Coal-measure sandstones is extremely liable 

 to vary, and also that appearances of unconformity in Coal-measures 

 are peculiarly liable to be deceptive. In the discussion which 

 followed the reading of a paper by Mr. Kendall " On the Whitehaven 

 Sandstone Series " at the Geological Society, on February 20, 1895, 

 Mr. Strahan, of the Geological Survey, inclined to think that the 

 appearances in the Whitehaven cliffs indicated simply local erosion, 

 not unconformity of the least importance. He also thought the 



