Changes

==Depositional environments and facies analysis==

==Depositional environments and facies analysis==

Most fossil species required specific conditions of temperature, substrate, and surrounding medium to carry on their normal activities. When conditions differed from ideal, the species is not present or is not preserved. The types of sedimentary rocks deposited under specific environmental conditions are ''biofacies'' and are identified by their specific rock properties including fossils.<ref name=pt05r140>Scholle, P. A., Spearing, D., 1982, Sandstone depositional environments: AAPG Memoir 31, 410 p.</ref><ref name=pt05r141>Scholle, P. A., Bebout, D. G., Moore, C. H., 1983, Carbonate depositional environments: AAPG Memoir 33, 708 p.</ref>

Most fossil species required specific conditions of temperature, substrate, and surrounding medium to carry on their normal activities. When conditions differed from ideal, the species is not present or is not preserved. The types of sedimentary rocks deposited under specific environmental conditions are ''biofacies'' and are identified by their specific rock properties including fossils.<ref name=pt05r140>Scholle, P. A., Spearing, D., 1982, Sandstone depositional environments: [http://store.aapg.org/detail.aspx?id=627 AAPG Memoir 31], 410 p.</ref><ref name=pt05r141>Scholle, P. A., Bebout, D. G., Moore, C. H., 1983, Carbonate depositional environments: [http://store.aapg.org/detail.aspx?id=656 AAPG Memoir 33], 708 p.</ref>

Fossils most commonly used in hydrocarbon exploration are microfossils (generally smaller than about 2 mm) because they can be recovered from drill cuttings without much damage to the fossils. Different processing techniques separate calcareous, siliceous, phosphatic, and organic-walled fossils.<ref name=pt05r100>Kummel, B., David, R., eds., 1965, Handbook of paleontological techniques: San Francisco, CA, W. H. Freeman, 852 p.</ref><ref name=pt05r55>Feldman, R. M., Chapman, R. E., Hannibal, J. T., eds., 1989, Paleotechniques: The Paleontological Society Special Publication No. 4, 358 p.</ref>

Fossils most commonly used in hydrocarbon exploration are microfossils (generally smaller than about 2 mm) because they can be recovered from drill cuttings without much damage to the fossils. Different processing techniques separate calcareous, siliceous, phosphatic, and organic-walled fossils.<ref name=pt05r100>Kummel, B., David, R., eds., 1965, Handbook of paleontological techniques: San Francisco, CA, W. H. Freeman, 852 p.</ref><ref name=pt05r55>Feldman, R. M., Chapman, R. E., Hannibal, J. T., eds., 1989, Paleotechniques: The Paleontological Society Special Publication No. 4, 358 p.</ref>