Mudrock
Mudrocks make up most of the sedimentary rocks on Earth.[1] They are a class of fine grained siliciclastic sedimentary rocks.
The types of mudrocks include: siltstone, claystone, mudstone, slate, and shale.
Most of the particles are less than 0.0625 mm (1/16th mm or 0.0025 inches) and are too small to study readily in the field. At first sight the rock types look quite similar; however, there are important differences in composition and naming.
There has been a great deal of disagreement about the classification of mudrocks. There are some reasons for this:
- Mudrocks are the least understood, and one of the most understudied sedimentary rocks to date
- It is difficult to study mudrock constituents, due to their tiny size
- And most importantly, there is more than one classification scheme accepted by scientists
Mudrocks make up half of the sedimentary rocks in the geologic record, and are easily the most widespread deposits on Earth. Fine sediment is the most abundant product of erosion, which is why mudrocks are so common.[1]
With increased pressure over time the platey clay minerals may become aligned, with the appearance of parallel layering (fissility). This finely bedded material which splits readily into thin layers is called shale, as distinct from mudstone.[2]
From the beginning of civilization, when pottery and mudbricks were made by hand, to now, mudrocks have been important. The first book on mudrocks was not published until 1964. However, scientists, engineers, and oil producers have understood the significance of mudrocks since the discovery of the Burgess Shale and the relatedness of mudrocks and oil.[3]
Mudrock Media
Glacial Lake Missoula claystone
Red mudrock in the Ragged Reef Formation (Pennsylvanian), Cumberland Basin, Nova Scotia
Photographer: Siim Sepp*Date of the creation: 19th April, 2005. This rock is a property of museum of geology of University of Tartu.
Pyrite*Locality: Millstream Station, Pilbara Region, Western Australia, Australia (Locality at mindat.org)*Size: 9.5 x 9.2 x 3.7 cm.*Two attractive complex balls of Pyrite crystals set beautifully against a black shale matrix. The larger ball is about 3.7 cm across, and the smaller perfec
Slate roof in Andorra.
Mississippi River Delta from space. This image was acquired on May 24, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. Hurricanes Katrina and Rita destroyed much of the Mississippi River Delta in 2005.
Related pages
References
- ↑ 1.0 1.1 Boggs, S. (2005). Principles of sedimentology and stratigraphy (4th ed.). Upper Saddle River, N.J.: Prentice Hall. ISBN 0130996963.
- ↑ Schieber J; Zimmerle W. & Sethi P. 1998. Shales and mudstones. Stuttgart: E. Schweizerbartsche Verlagsbuchhandlung. ISBN 3-510-65183-9
- ↑ Potter P.E; Maynard J.B. & Depetris P.J. 2005. Mud and mudstones: introduction and overview. Wurzberg, Germany: Springer. ISBN 3-540-22157-3