202 D. Jones — Denudation of Coolhrook-dale. 



table showing the niiraber of strata passed through and their total 



thickness as follows : — 



Depth. No, of strata. 



Lightmoor 460 feet. 46 



Dawley 450 „ 58 



Malinslee 560 „ 51 



"Wombridge 540 „ 70 



New Hadley 440 „ 57 



Donington Wood 560 „ 60 



To which is added the following note — " The minuter sub-divisions 

 in these sections not being generally given as they are at Madeley, 

 will account for the disproportion between the thickness and number 

 of the strata, and in one stratum at one pit may be included several 

 of an adjoining pit." This may be the case ; but I would observe 

 that in the sections given a much larger proportion of older Coal- 

 measures are met with than at Madeley, which measures generally 

 have strata of greater thickness than the upper series. The Fun- 

 gous Coal is the highest of the older Coal-seams in the district, and 

 the Chance Pennystone the highest workable ironstone of the older 

 strata. From the surface to the Chance Pennystone at New Hadley 

 is 109 feet, about 80 feet of which is alluvium, and described as 

 " wild red ground." At Hills-lane I consider that the whole of the 

 strata from the Chance Pennystone to the Penny-measures proper 

 have been removed by denudation, and the space has been since 

 filled up with Coal-measure of the younger age, which consists of 

 much thinner strata, and this accounts for the much greater number 

 of strata in the southern portion. The geological horizon for these 

 younger Coal-measures is of course above the Chance Pennystone. 

 The persistency of the Clod Coal is remarked upon : this is due to 

 the fact that being low in the series it escaped to a greater extent 

 the denudation which overtook the higher strata. " If it were not 

 for the Pennystone, Clod Coal, Best Coal, and one or two more beds, 

 which serve as landmarks throughout the whole Coal-field," says Mr. 

 Prestwich, " it would be difficult to recognize the connexion between 

 the Donington district and the Malinslee, or between the Malinslee 

 and the Madeley or the Broseley. The difi'erence between the Amies 

 and Donington sections is still more striking, and placed side by side 

 they appear totally distinct." This is not surprising, seeing that at 

 Amies only 79 feet of older Coal-measures exist, instead of about 384 

 feet, as at Donington. " 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." 

 " The Chance Pennystone, which is 8 feet thick at Wombridge, is 

 unknown at Malinslee," By reference to the map it will be seen 

 that it has been denuded from the Malinslee district. 



Mr. Prestwich points to the phenomena of the Symon fault in the 

 neighbourhood of Malinslee, but it remained for Mr. Scott to point 

 out that it was caused by the denudation of the older Coal-measures. 



