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One definition is that siltstone is mudrock (clastic sedimentary rock containing at least 50% clay and silt) in which at least 2/3 of the clay and silt fraction is composed of silt-sized particles. Silt is defined as grains 2–62 μm in diameter, or 4 to 8 on the Krumbein phi (φ) scale. [7] An alternate definition is that siltstone is any ...
Siltstone at UAT, Estonia. A siltstone is a lithified, non-cleavable mudrock. In order for a rock to be named a siltstone, it must contain over fifty percent silt-sized material. Silt is any particle smaller than sand, 1/16 of a millimeter, and larger than clay, 1/256 of millimeter.
The term was earlier used by geologists to describe a clay-rich, fine-grained clastic sediment or sedimentary rock, i.e. mud or a mudstone, the metamorphosed version of which would technically have been a metapelite. It was equivalent to the now little-used Latin -derived term lutite. [4][5][6] A semipelite is defined in part as having similar ...
Pages in category "Siltstone formations" The following 200 pages are in this category, out of approximately 331 total. This list may not reflect recent changes .
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. [1] Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when dry, and lacks plasticity when wet. Silt can also be felt by the tongue as granular when placed ...
The Winterburn Group is composed of silty dolomite, evaporite, argillaceous limestone, red and green siltstone, anhydrite, silty dolomite and siltstone. Pinnacle reefs develop in the Nisku Formation. [1]
The Mercia Mudstone Group is an early Triassic lithostratigraphic group (a sequence of rock strata) which is widespread in Britain, especially in the English Midlands —the name is derived from the ancient kingdom of Mercia which corresponds to that area. It is frequently encountered in older literature as the Keuper Marl or Keuper Marl Series ...
The oldest beds of this formation belong to the Dinosaur Canyon Member, a reddish, slope-forming rock layer with thin beds of siltstone that are interbedded with mudstone and fine sandstone. [11] The Dinosaur Canyon, with a local thickness of 140 to 375 feet (43 to 114 m), was probably laid down in slow-moving streams, ponds and large lakes. [7]