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Tree remains that have undergone petrifaction, as seen in Petrified Forest National Park. In geology, petrifaction or petrification (from Ancient Greek πέτρα (pétra) 'rock, stone') is the process by which organic material becomes a fossil through the replacement of the original material and the filling of the original pore spaces with minerals.
In geology, silicification is a petrification process in which silica-rich fluids seep into the voids of Earth materials, e.g., rocks, wood, bones, shells, and replace the original materials with silica (SiO 2).
In some instances, the original structure of the stem tissue may be partially retained. Unlike other plant fossils, which are typically impressions or compressions, petrified wood is a three-dimensional representation of the original organic material. The petrifaction process occurs underground, when wood becomes buried in water or volcanic ash.
In order to determine the likelihood of oil/gas generation, therefore, the thermal history of the source rock must be calculated. This is performed with a combination of geochemical analysis of the source rock (to determine the type of kerogens present and their maturation characteristics) and basin modelling methods, such as back-stripping ...
Fossil water can potentially dissolve and absorb a number of ions from its host rock. Salinity in groundwater can be higher than seawater. [5] In some cases, some form of treatment is required to make these waters suitable for human use. Saline fossil aquifers can also store significant quantities of oil and [6] natural gas. [7]
Petrification is associated with the legends of Medusa and the Svartálfar among others. In fairy tales, characters who fail in a quest may be turned to stone until they are rescued by the successful hero, as in the tales such as The Giant Who Had No Heart in His Body, The Water of Life and The Dancing Water, the Singing Apple, and the Speaking Bird, as well as many troll tales.
Fossil fuel divestment or fossil fuel divestment and investment in climate solutions is an attempt to reduce climate change by exerting social, political, and economic pressure for the institutional divestment of assets including stocks, bonds, and other financial instruments connected to companies involved in extracting fossil fuels.
Similar, but different in origin, is the concept of fossil water, which is used to describe very old groundwater found in deep aquifers or bedrock. Typically it was recharged during a different climatic period (e.g., the last ice age ) so is also very old, but possibly not of the same genesis as the rock.