Mississippian (geology)

The Mississippian (/ˌmɪs.ɪˈsɪp.i.ən/ miss-ih-SIP-ee-ə-n,[5] 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 Valley.

Mississippian
358.9 ± 0.4 – 323.2 ± 0.4 Ma
Chronology
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitSubperiod
Time span formalityFormal
Lower boundary definitionFAD of the Conodont Siphonodella sulcata (discovered to have biostratigraphic issues as of 2006)[2]
Lower boundary GSSPLa Serre, Montagne Noire, France
43°33′20″N 3°21′26″E / 43.5555°N 3.3573°E / 43.5555; 3.3573
GSSP ratified1990[3]
Upper boundary definitionFAD of the Conodont Declinognathodus nodiliferus
Upper boundary GSSPArrow Canyon, Nevada, United States
36°44′00″N 114°46′40″W / 36.7333°N 114.7778°W / 36.7333; -114.7778
GSSP ratified1996[4]

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.[6]

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. The USGS geologic time scale shows its relation to other periods.[7]

In Europe, the Mississippian and Pennsylvanian are grouped together as the Carboniferous system, and traditionally referred to as the Upper Carboniferous and Lower Carboniferous instead.

SubdivisionsEdit

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:

ReferencesEdit

  1. ^ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
  2. ^ Kaiser, Sandra (1 April 2009). "The Devonian/Carboniferous boundary stratotype section (La Serre, France) revisited". Newsletters on Stratigraphy. 43: 195–205. doi:10.1127/0078-0421/2009/0043-0195. Retrieved 7 December 2020.
  3. ^ Paproth, Eva; Feist, Raimund; Flajs, Gerd (December 1991). "Decision on the Devonian-Carboniferous boundary stratotype" (PDF). Episodes. 14: 331–336.
  4. ^ Lane, H.; Brenckle, Paul; Baesemann, J.; Richards, Barry (December 1999). "The IUGS boundary in the middle of the Carboniferous: Arrow Canyon, Nevada, USA" (PDF). 22: 272–283. Retrieved 8 December 2020. Cite journal requires |journal= (help)
  5. ^ "Mississippian". Dictionary.com Unabridged. Random House.
  6. ^ Cesare Emiliani, Planet Earth: Cosmology, Geology, and the Evolution of Life and Environment 1992 496.
  7. ^ USGS Timescale

External linksEdit