Page:VCH Northamptonshire 1.djvu/43

 GEOLOGY places clay balls crowded with fossils, at all angles, which they had picked up whilst rolling in a soft condition, indicating nearness of actual denudation. Finally, in the Northampton Sand we have the representative of the Marlstone rock-bed, by its fossils linked to the beds below, and with wood and ironstone indicating nearness to land ; its coral reefs, slates made of calcareous sandy mud, beds of comminuted shell, and layers of small pebbles all pointing to shallow, warm water. An abbreviated section of the Upper Lias is given below ; further particulars may be obtained from other sources.^ TYPICAL SECTION OF UPPER LIAS Zone Name of Bed or Zone Description of the Beds Approximate maximum thickness in feet 'Opalinus' Zone Northampton Sand Zone « Lilli ' Zone (Buckman) 1. Layer ofnodules, some bored, some phosphatized. 2. Micaceous sandy clay, with layers of nodules, thin oyster beds, clay balls ; many Inferior Oolite fossils 3. Layer of water-worn nodules, bleached, some covered with ostrea or with serpulce 24 Leda-ovum Beds 4. Blue clay, with nodules, Leda-ovum, and many ammonites ; Cerithium armatum and other gasteropods in lower 30 ft. 72 'Communis' Unfossiliferous Beds 5. Blue clay, with large nodules, much nail-head ipar, and few fossils 76 Communis Beds 6. Argillaceous limestone passing into shale, or even clay ; many fossils, especially ammonites 7. Somewhat calcareous clay, with oolitic concre- tions, many small specimens of Ammonites com- munis and other ammonites of the same group 5 ' Serpen- Serpentinus Beds 8. Hard, argillo-calcareous stone, with large am- monites of the Harpoceras group, etc. 9. Light-coloured marl, very few fossils 5 tinus ' Zone Fish Beds 10. Paper shales, dark or light-coloured according to weathering, with fish remains 11. Fish Beds, one or two, fine grained limestones, nodular or persistent, with ammonites and fish remains 2 .84 Soc, vol. iii. pp. 3, 183, 299; vol. iv. pp. 16, 27, 215 ; vol. v. p. 54 ; vol. vi. p. 96; 'Report on some Liassic Beds in Northamptonshire,' Report Brit. Assoc, 1S91, pp. 334-351- 13
 * Jurensis '
 * Beeby Thompson, ' The Upper Lias of Northamptonshire,' Journ. North. Nat. Hist.