Geology of Coalbrook Dale. 4oi 



linslee, or between the Malinslee and the Madeley or the Broseley. The 

 ditFerence between the Amies and Donnington sections is still more striking, 

 and placed side by side they appear totally distinct. (Diagram, PI. XXXVII.) 

 It is singular to observe the great and rapid variations in the importance and 

 lithological character of the larger portion of the strata composing these coal- 

 measures. One stratum will gradually disappear, whilst a thin one will rapidly 

 acquire a thickness of several feet, and will again frequently wedge out. In 

 some places, as at Priorslee, the clod, middle, and best coals are separated by 

 only a few inches of shale, and can consequently be worked as one seam, and 

 in the same level; whilst at New Hadle}-, Broseley, and other localities, they 

 are separated by 4 to 10 feet of shale or sandstone. The Chance Penney- 

 stone, which is 8 feet thick at Woombridge, is unknown at IMalinsIee. In the 

 former district 23 feet of sandstone and shale are interposed between the 

 " white flat measure " and the " flint coal," whilst at Malinslee they are in 

 immediate superposition : at the latter point there are 102 feet between the 

 " brick measures" and the " double coal," though at Woombridge only 36 

 feet. The following table exhibits the thickness in feet of the strata between 

 the Penneystone measure and the clod coal, commencing north and proceed- 



Donnington Hadley Malinslee DaT\ley Lightmoor Madeley Broseley 

 Thickness of Strata between tliel 



,^, ,^ I 44 3G 32 54 60 72 94 



r enney stone and LlodLoal. . J 



Thickness of the Penneiistone ") 



,, '' -^ I 31 21 19 18 16 6 4 



Measure J 



A singular instance of rapid variation occurs at Ketley and Arleston, in 

 the upper and lower chinches. At Woombridge and New Hadley the thick- 

 ness of these strata is 20 feet, whereas near the Ketley furnaces it amounts to 

 126 feet, and at Arleston to 120 feet; but at Lawley it again decreases to 21 

 feet, and at Little Wenlock to 15 feet. Amidst all these indications of rapid 

 changes, the persistence over large areas of the lower coal-beds, especially 

 the clod coal, is remarkable. The upper coals are, as before stated, more 

 irregular in thickness and extent, though far more constant in their range, 

 than the other strata. In the old Park, an instance, however, occurred of a 

 bed of coal six feet thick gradually thinning off, and extending through an 

 area of only 300 yards by 40 yards. 



It would be an almost impracticable task to enumerate all the changes exhibited in every part 

 of the field ; I have therefore attempted to form a diagram (PI. XXXVII.) which connects and 

 dovetails the principal sections of the coal-field from Donnington to Caughley ; and an inspection 

 of it may convey a clearer idea of the structure of the coal formation than could be derived from a 



