Search results
Results from the WOW.Com Content Network
The grade of coal produced depended on the maximum pressure and temperature reached, with lignite (also called "brown coal") produced under relatively mild conditions, and sub-bituminous coal, bituminous coal, or anthracite coal (also called "hard coal" or "black coal") produced in turn with increasing temperature and pressure. [2] [22]
The Carboniferous rainforest collapse was caused by a cooler drier climate that initially fragmented, then collapsed the rainforest ecosystem. [2] During most of the rest of Carboniferous times, the coal forests were mainly restricted to refugia in North America (such as the Appalachian and Illinois coal basins) and central Europe.
Coal forms when organic matter builds up in waterlogged, anoxic swamps, known as peat mires, and is then buried, compressing the peat into coal. The majority of Earth's coal deposits were formed during the late Carboniferous and early Permian. The plants from which they formed contributed to changes in the Carboniferous Earth's atmosphere. [25]
Carbon can be produced in stars at least as massive as the Sun by fusion of three helium-4 nuclei: 4 He + 4 He + 4 He --> 12 C. This is the triple alpha process. In stars as massive as the Sun, carbon-12 is also converted to carbon-13 and then onto nitrogen-14 by fusion with protons. 12 C + 1 H --> 13 C + e +. 13 C + 1 H --> 14 N.
Although living species are small, during the Carboniferous, extinct tree-like forms (Lepidodendrales) formed huge forests that dominated the landscape and contributed to coal deposits. The nomenclature and classification of plants with microphylls varies substantially among authors.
A coal ball. Carbonate mineralization involves the formation of coal balls. Coal balls are the fossilizations of many different plants and their tissues. They often occur in the presence of seawater or acidic peat. Coal balls are calcareous permineralizations of peat by calcium and magnesium carbonates. Often spherical in shape and ranging from ...
In geology, cyclothems are alternating stratigraphic sequences of marine and non-marine sediments, sometimes interbedded with coal seams. The cyclothems consist of repeated sequences, each typically several meters thick, of sandstone resting upon an erosion surface, passing upwards to pelites (finer-grained than sandstone) and topped by coal.
The Group comprises a lower unit of coarse sandstones, siltstones, mudstone, and limestones with thin coals and ironstones known as the Lower Limestone Formation, an overlying sequence of similar rocks known as the Limestone Coal Formation, then an Upper Limestone Formation and at its top the sandstones of the Passage Formation.