Beviews — Geology of Ollerton. 229 



wolfram have been obtained from the alluvial deposits on and near to 

 the Bodmin Moor granite. A full account is given of the various 

 mines of tin, copper, lead, silver, manganese, etc., with plans and 

 statistics. Building-stones, slates (mostly Carboniferous), and other 

 economic deposits are described, and a short account is given of water- 

 supply derived from granite areas. 



III. — Geological Survey of Great Britain. 

 2. The Geology of the Country around Ollerton. By G. W. Lamp- 

 LtTGH, F.E.S., J. B. Hill, R.N., W. Gibson, D.Sc, E,. L. Sherlock, 

 D.Sc, and B. Smith, M.A. 8vo ; pp. v, 93, with 6 text-illustra- 

 tions and 4 plates. 1911. Price 2s. 



OLLERTON is situated on the Bunter Pebble-beds of Sherwood 

 Forest, and lies in the northern part of the area represented on 

 the colour-printed map. Sheet 113, accompanying this memoir. 



The area is foi'raed almost wholly of Permian and Triassic strata, 

 for there is but a tiny portion of Lower Lias in the south-eastern 

 corner, and the Coal-measures, worked at Warsop, do not appear at 

 the surface, although they extend beneath the entire area probably 

 at a depth which nowhere exceeds 4,000 feet. The map shows the 

 Drifts, but we have never seen a 1 inch sheet with glacial deposits, 

 which shows less Boulder-clay, gravel, and sand. The Trent River 

 on the east is naturally bordered by Alluvium and Valley gravel ; 

 there are tracts of tufa in the Alluvium near Caunton and Tuxford, 

 and there are deposits of Blown Sand bordering the Trent and 

 apparently derived from the liver flat. 



An interesting marine bed is described as occurring above the Top 

 Hard Coal in a shaft at Mansfield Colliery, the most abundant fossils 

 belonging to species which occur below the Millstone Grit. Some 

 diff'erences of opinion are expressed with regard to the relations 

 between Permian and Trias. Mr. Hill sees local indications of un- 

 conformity, whereas Dr. Sherlock considers that the upper part of the 

 Permian in the northern district is equivalent to the lower part of 

 the Bunter further south. The Bunter Pebble-beds, which yield a dry 

 sandy soil, extend through that part of Sherwood Forest known as 

 the 'Dukeries', and noted for its beautiful parks and fine timber. 

 The lower portion of the Iveuper is termed ' Waterstones', though 

 Lower Keuper Sandstone would seem a more appropriate general 

 term. The Keuper Marls contain gypsum and layers of hard 

 dolomitic sandstone or ' skerries ', the outcrops of which are indicated 

 on the map by lines. Rhsetic beds occur over a small area, including 

 the Avicula-contorta shales and overlying marls and pale limestone 

 that, despite the doubts of Mr. L. Richardson, may reasonably be 

 regarded as representing the White Lias. 



We are glad to see attention given to the organic remains 

 (mammals, mollusca, and plants) of the Alluvial deposits, including 

 also human remains and celts. The older Valley gravels do not 

 appear locally to have yielded any fossils, but the authors discuss the 

 changes indicated since the river was establiBhed. Economic geology 

 has a useful section on soils and asriculture ; there are records of 



