of Derbyshire and Notts Coalfield. 



291 



The latter consists of a few feet of pyritous shale, with calcareous 

 and pyritous nodules, containing numerous marine fossils of which the 

 most common are Pterinopecten papyraceus, Goniatites, Lingula, and 

 the remains of fish. 



This marine bed provides a reliable and easily recognized datum- 

 line for these lower measures, the base of which is clearly defined by 

 the upper limit of the massive and persistent First Grit (Rough Rock). 



Detailed Consideration or Sinkings and Borings. 

 So long ago as 1856 Smyth (3) gave for the Stanton district the 

 following estimate for the thickness of the measures between the 

 Kilburn Coal and the ' Bottom ' Coal which " rests almost immediately 

 upon the Millstone Grits " : — 



Kilburn Coal 



Clunch 



Honeycroft Kake 



Measures . 



Civilly Rake 



Coal, ' Furnace ' (Naughton Coal) 



Dale Moor Rake 



Measures ..... 



Coal, ' Bottom ' (Alton Coal) 



Total 



486 3 



Subsequent explorations, whilst confirming the above estimate, 

 have proved a further 50 feet of Coal-measures between the Alton Coal 

 and a coal — the Belperlawn seam — which occurs on the top of the 

 First Grit. 



Trial Shaft at Stanton Gate Iron Works. (Fig. I, Section IV.)— This 

 shaft was sunk on the outcrop of the Kilburn Coal in 1877, at a time 

 when much valuable local knowledge of the Lower Coal-measures had 

 been obtained during the working of the numerous ironstone pits of 

 the district. 



This section is of importance, because the coal-seams, Ganister beds, 

 and ironstone ' rakes ' are correctly named and carefully described. 

 The thickness of measures between the Kilburn and Alton Coals 

 amounts to 480 feet, thus confirming Smyth's estimate of 1856. 



Wollato7i Colliery, — An old boring from the bottom of this shaft 

 proved the measures from the Deep Hard Coal down to the Naughton 

 Coal. The Black Shale (Silkstone) seam was proved, but no trace 

 of the Kilburn Coal was found on the horizon where it was 

 expected to occur. 



The Little Hallam Boring near Ilkeston. (Fig. 1, Section III, and 

 Fig. 2, Section IV.) — This deep boring for water was put down in 1896 

 by the Corporation of Ilkeston on a site between the outcrops of the 

 Black Shale and the Kilburn Coals about three-quarters of a mile 

 south of the town. 



The first 500 feet were cut by percussive drill, and " as this part of 

 the section was well known it was not accurately observed" (4); for 

 this reason the measures above the Kilburn Coal ^ will not be considered 



The thickness of this coal as given in the boring section is probably incorrect. 



