GEOLOGY 



If we allow 30 feet for the unknown thickness of drift with which they 

 are covered, the solid rock rises to 538 feet near Annesley, 595 feet on 

 the Robin Hood's Hills (their highest point) and 558 feet west of Mans- 

 field. From these elevations they gradually slope to north and south but 

 more especially towards the east, exposing a broad dip slope. This, worn 

 into irregular hills and possibly undulating also, forms the wild sandy 

 forest land for which Nottinghamshire is famous. 



It is this large catchment area of more than 120 square miles, 

 together with the porosity of the rock, which makes the Pebble Beds and 

 underlying Red Sandstones so valuable for water supply. The larger 

 part of the rainfall sinks in at once and has a free passage, so that there 

 are but few streams on the surface, which is but sparsely inhabited, and 

 little injury to agriculture can result from the extraction of water. The 

 lower parts are thus saturated by available water and afford an almost 

 inexhaustible supply. At the same time the reservoir itself forms its 

 own admirable filter bed, and the water comes out with only the mineral 

 impurities dissolved in its passage through the rock, which are not on 

 the average great. The amount extracted in 1893 amounted to more 

 than 5,000,000 gallons daily for the use of the borough of Nottingham, 1 

 while at the boring at South Scarle the water rose in a fountain above 

 the surface from a depth of 960 1,440 feet. 



The origin of the Pebbles in the Bunter. This is a subject which has 

 been much discussed, but it cannot be said that any satisfactory solution 

 has been arrived at. A similar question might be asked concerning the 

 materials of any stratum, e.g. the Millstone Grit, and it would be equally 

 hard to answer. In the present case, however, hopes of a solution are 

 raised by the size of the pebbles, which are large enough to show any 

 special characters of the rock whence they are derived, whether litho- 

 logical or palasontological. With regard to the lithological characters 

 the bulk of the pebbles are of quartzite, many of which are of a peculiar 

 liver-coloured tint, and others are whiter or of vein quartz. These as a 

 rule afford very little guide, as ' one quartzite is very like another.' 

 The rarer pebbles are of ' green and black slates, jaspers, gneiss, sub- 

 angular blocks of sandstone, rounded greenstone and felstone ' (Irving), 

 Millstone Grit, Yoredale Sandstone, Caradoc Sandstone, amygdaloidal 

 lava, chert, white granite, volcanic ash, and toadstone (Shipman). 

 Palaeontologically they have been found to contain Ortbis budleighensis, 

 0. Jiabellulum, O. calligramma, Atrypa cf. reticularis, Stropbomena grandis 

 and Glyptocrinus basalts from pre-Carboniferous rocks and Lonsdaleia Jiori- 

 formis from the Carboniferous Limestone. 



Neither these rocks nor these fossils could have come from the 

 north down the east side of the Pennine axis from any rocks now 

 exposed in situ, for there are none such containing them. They probably 

 came from the west, as indicated by the prevailing falsebedding, or in 

 part from the north-west. The exact locality of the land of their origin 



1 Hull, Report Brit. Asm. 1895, p. 743. 

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