Mississippian (geology)

The Mississippian (/ˌmɪs.ɪˈsɪp.i.ən/ miss-ih-SIP-ee-ə-n,[2] also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earlier/lower of two subperiods of the Carboniferous period lasting from roughly 358.9 to 323.2 million years ago. As with most other geochronologic units, the rock beds that define the Mississippian are well identified, but the exact start and end dates are uncertain by a few million years. The Mississippian is so named because rocks with this age are exposed in the Mississippi River valley.

"Mississippian period" and "Early Carboniferous" redirect here. For the North American civilization, see Mississippian culture.
Mississippian Epoch
358.9–323.2 million years ago
Ages in the Mississippian
-360 —
–
-355 —
–
-350 —
–
-345 —
–
-340 —
–
-335 —
–
-330 —
–
-325 —
–
Ages of the Mississippian.
Axis scale: millions of years ago.
System Subsystem/
Series		 Stage Age (Ma)
Permian Cisuralian Asselian younger
Carboniferous Pennsylvanian Gzhelian 298.9 303.7
Kasimovian 303.7 307.0
Moscovian 307.0 315.2
Bashkirian 315.2 323.2
Mississippian Serpukhovian 323.2 330.9
Visean 330.9 346.7
Tournaisian 346.7 358.9
Devonian Late Famennian older
Subdivision of the Carboniferous system
according to the ICS, as of 2017.[1]

The Mississippian was a period of marine transgression in the Northern Hemisphere: the sea level was so high that only the Fennoscandian Shield and the Laurentian Shield were dry land. The cratons were surrounded by extensive delta systems and lagoons, and carbonate sedimentation on the surrounding continental platforms, covered by shallow seas.[3]

In North America, where the interval consists primarily of marine limestones, it is treated as a geologic period between the Devonian and the Pennsylvanian. During the Mississippian an important phase of orogeny occurred in the Appalachian Mountains. It is a major rock-building period named for the exposures in the Mississippi Valley region. The USGS geologic time scale shows its relation to other periods.[4]

In Europe, the Mississippian and Pennsylvanian are one more-or-less continuous sequence of lowland continental deposits and are grouped together as the Carboniferous system, and sometimes called the Upper Carboniferous and Lower Carboniferous instead.

Subdivisions

In the official geologic timescale, the Mississippian is subdivided into three stages:

The lower two come from European stratigraphy, the top from Russian stratigraphy. Besides Europe and Russia, there are many local subdivisions that are used as alternatives for the international timescale. In the North American system, the Mississippian is subdivided into four stages:

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References
  1. http://www.stratigraphy.org/index.php/ics-chart-timescale
  2. "Mississippian". Dictionary.com Unabridged. Random House.
  3. Cesare Emiliani, Planet Earth: Cosmology, Geology, and the Evolution of Life and Environment 1992 496.
  4. USGS Timescale


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