part 4] MICROSCOPIC MATEIIIAF. of BL'>TEli PEBBLE-EEDS. 333^ 



the IMansfield-Southwell biancli of tlie Midland liaihvay. betvN-een 

 Maiistield and Python Hill, 3 or 4 miles of excellent sections show 

 marked cross-bedding dipping south-eastwards. i 



In the district about Nottingham the dip of the false bedding 

 shows a general direction to^^'ayds the south-east.- 



There are subordinate currents which come f]-om the south-west 

 and south-east respectively, as, for example, in the Farnsfield 

 district.^ 



The general direction of the current-bedding is towards the east 

 in the northern part of the county, and veers towards the south- 

 east from the Grorsethorpe district, where the main easterly current 

 bifurcates, as we proceed in the direction of Nottingham. 



The thickest part of the formation, as shown by bore- 

 holes. — East of the Pennines, as proved by boreholes and shaft- 

 sinkings,* the Nottinghamshire Pebble-Beds are thickest at Bever- 

 cotes and Kelham, being 568 feet thick at the former, and 471 

 feet thick at the latter place. ^ 



This thickest part is, in the main, in the line of the prevailing 

 currents, indicated hj the distribution of the heavy minerals and 

 the general dip of the false bedding (see map and table, p. 332). 



' North of Bevercotes the Bunter Pebble-Bed assumes all the 

 characters of the Lower Mottled Sandstone ' ; ^ while south of 

 Thurgarton '' the entire Bunter, as proved, is thinner than the 

 Pebble-Beds in the localities named above. 



The mineral grains and the possible sources of their 

 supply. — The outstanding mineralogical fact is the abundance of 

 stam'olite. For this there is no adequate source of supph^ locally. 

 Kagged patches occur at Sinen Gill — in the Skiddaw Granite 

 series.^ 



I have not been able to discover it in the South Pennines, where 

 I have searched for it in the Cromford neighbourhood of Derby- 

 shire. It appears, however, to be abundant in Scotland, being- 

 found in several localities,^ from Unst in the north-east, roughly in 

 a south-westerly direction to Mull. 



' 'The Geology of the Country around OUerton ' Mem. Geol. Surv. 1911, 

 p. 22. 



- 'The Geolo'gy of the Coimtry between Newark & Nottingham' Ibid. 1908, 

 p. 31. -^ Ibid. 1911, p. 22. 



"* These thicknesses are approximate ; but they are the nearest procurable 

 approximations, and, when used for purposes of comparison with known facts 

 in the district in question, are certainly of much interest and importance, if 

 not of exact and accurate evidence in themselves. 



^ 'The Geology of the Country around Ollerton ' Mem. Geol. Surv. 1911, 

 p. 18. 



^ W. Gibson, ' The Concealed Coalfield of Yorkshire & Nottinghamshire ' 

 1913, p. 31. ' Ibid. p. 33. 



« F. H. Hatch & U. H. Rastall, ' Petrology ' vol. ii (1913) p. 248. 



y M.F. Heddle, ' Mineralogy of Scotland' vol. ii(1901) p. 75 & ibid. Supple- 

 ment, p. 209 ; G. Barrow, Q. J. G. S. vol. xlix (1893) p. 340 & ibid. pp. 349, 

 350 ; T. 0. Bosworth, Q. J. G. S. vol. Ixvi (1910) p. 394. 



