| 词汇 | mudstone |
| 释义 | mudstone noun[ C or U ] geology specializeduk /ˈmʌd.stəʊn/ us /ˈmʌd.stoʊn/ a type of rock made from clay or mud(= earth that has been mixed with water): The rocks included limestone, sandstone, and mudstone. Mudstones make up two-thirds of all sedimentary rocks. The bone, embedded in mudstone, is probably part of a new dinosaur species. There are black mudstones interbedded with the siltstones. Desiccation cracks in the mudstones show that the lakes dried out periodically. The effect was to release the pressure in the aquifer, causing the water to push out through the mudstone, creating a volcano of mud. Geology: types of rock agglomerate arenaceous arenite asthenosphere asthenospheric emery flinty gneiss indurated intrusive lahar limestone lodestone magma marcasite marl marmoreal obsidian sandstone schist Examples of mudstonemudstone The pale green tuffaceous mudstone beds are medium bedded and contain abundant radiolarian fossils. 483 parallel, sometimes cross-bedded sandstone, with thin, laterally pinching out red mudstone is also observed. This facies pinches out laterally and shows sharp contact with the bentonite facies (sections 5, 6) and tuffaceous mudstone facies (section 9). These ponds are filled by clay-fractionrich suspension load, producing mottled mudstone. The bentonite facies is composed of five subfacies including tuffaceous mudstone, nodular bentonite, sandy bentonite, clayey bentonite and pure bentonite. Occasionally thin, very poorly sorted tuffaceous mudstone beds with subtle normal grading and sharp bases are present. The basin plain consists of the finest material of the fan (mudstone-siltstone) and represents the most distal parts. Isolated mudstone cross-beds record the temporary ponding of a channel. Our material contains hundreds of priapulid worms found on closely associated bedding surfaces in mudstone. The conglomerate grades into laminated greenish/dark grey mudstone at a horizon approximately 87 m above the base through sandstone. In all three basins, this mudstone-dominated interval passes into sandstonedominated sediments of a braided fluvial system. Ammonoids are preserved as imprints on mudstone bedding planes. The upper bedding planes generally grade into mudstone, which in places is bioturbated. These sandstones often have mudstone flakes or clasts, accompanied by a scattering of plant remains and marine fauna. Two available specimens are preserved in yellowish green mudstone as flattened compressions. These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors. |
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