MILITARY GEOLOGY 475 polytungstate, the density of which is altered by the addition of water To separate conodonts, for example, a liquid with a specific gravity of about 2.75 is used; this allows calcite to float and the conodonts to sink The specific gravity of pollen ranges from just over to about 1.5, whereas the minerals encountered in pollen analyses have specific gravities ranging from 2.0 to over 3.0 (gypsum, 2.3; feldspar, 2.55; quartz, 2.6; calcite, 2.7; dolomite, 2.8) Therefore, a solution specific gravity between 1.56 and 2.0 should be used for pollen separation Picking The final stage in any processing of the groups of large microfossil is that of picking the specimens This is usually carried out by thinly spreading out the residue on a flat plate such that each grain can be easily seen, and then using a low-power binocular microscope at 10–20Â magnification, scanning each grain to identify the microfossils When a specimen is spotted, it is removed by using a fine, sable-hair brush of gauge 000 that has been wetted in distilled water The specimen is transferred onto a numbered gridded slide that has been prepared with some adhesive Gum tragacanth with a mould inhibitor has been widely used, but water-soluble glues such as Pritt Stick work just as well Alignment and careful arrangement of the specimens on the slide aids in identification and counting See Also Conservation of Geological Specimens Fossil Plants: Calcareous Algae Microfossils: Acritarchs; Chitinozoa; Conodonts; Foraminifera; Ostracoda; Palynology Sedimentary Environments: Depositional Systems and Facies Further Reading Aldridge RJ (1990) Extraction of microfossils In: Briggs DEG and Crowther PR (eds.) Palaeobiology A Synthesis, pp 502 504 Oxford: Blackwell Scientific Publications Allman M and Lawrence DF (1972) Geological Laboratory Techniques London: Blandford Austin RL (1987) Conodonts: Investigative Techniques and Applications Chichester: Ellis Horwood Limited Brasier MD (1980) Microfossils London: Allen and Unwin Feldman RM, Chapman RE, and Hannibal JT (1989) Paleo techniques The Paleontological Society Special Publica tion New Haven, CT: The Paleontological Society Green OR (2001) A Manual of Practical Laboratory and Field Techniques in Palaeobiology Dordrecht: Kluwer Academic Publishers Hodgkinson RL (1991) Microfossil processing: a damage report Micropaleontology 37(no 3): 320 326 Kummel B and Raup D (1965) Handbook of Palaeonto logical Techniques San Francisco: WH Freeman and Co Taylor RJ and Hamilton GB (1982) Techniques In: Lord AR (ed.) A Stratigraphical Index of Calcareous Nanno fossils, pp 11 15 Chichester: Ellis Horwood Limited MILANKOVITCH CYCLES See EARTH: Orbital Variation (Including Milankovitch Cycles) MILITARY GEOLOGY E P F Rose, Royal Holloway, University of London, Egham, UK ß 2005, Elsevier Ltd All Rights Reserved Introduction Throughout the nineteenth century, geology was widely perceived as a science with potential military applications However, geologists were not operationally deployed upon the battlefield until the two twentieth-century world wars Then, German forces made far greater use of military geologists than their British and American opponents, although the roles on both sides were similar Military geologists guided the quarrying of aggregates and other mineral resources for tactical or strategic use; the development of secure water supplies adequate to support troop concentrations; aspects of military engineering, particularly with regard to fortification and the construction of underground facilities; and terrain analysis, notably