All Topics  
Cryogenian

 

 
   Email Print
   Bookmark   Link
 

 

Cryogenian
 
 
  Topics Cryogenian Topic Home

The Cryogenian (from Greek
Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
 cryos "cold" and genesis "birth") is a geologic period that lasted from . The Sturtian and Marinoan glaciations, which are the greatest ice ages known to have occurred on Earth and may have covered the entire planet, occurred during this period. It was the second geologic
Geology

Geology is the science and study of the solid and liquid matter that constitute the Earth. The field of geology encompasses the study of the composition, structural geology, physical properties, dynamics, and History of the Earth of Earth materials, and the processes by which they are formed, moved, and changed....
 period of the Neoproterozoic
Neoproterozoic

The Neoproterozoic Era is the unit of geologic time scale from 1,000 to 542 +/- 0.3 million years ago. The terminal Era of the formal Proterozoic Eon , it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods....
 Era, preceded by the Tonian
Tonian

The Tonian is the first geologic geologic period in the Neoproterozoic era and lasted from 1000 annum to 850 Ma . Instead of being based on stratigraphy, these dates are defined by the International Commission on Stratigraphy based on radiometric dating....
 Period and followed by the Ediacaran
Ediacaran

The Ediacaran Period is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon....
. These so-called 'snowball earth
Snowball Earth

Snowball Earth refers to hypotheses regarding paleoclimate global-scale glaciation, claiming that the Earth's surface was nearly or entirely frozen at some points in its past....
' events are the subject of much scientific controversy.






Discussion
Ask a question about 'Cryogenian'
Start a new discussion about 'Cryogenian'
Answer questions from other users
Full Discussion Forum



Encyclopedia


The Cryogenian (from Greek
Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
 cryos "cold" and genesis "birth") is a geologic period that lasted from . The Sturtian and Marinoan glaciations, which are the greatest ice ages known to have occurred on Earth and may have covered the entire planet, occurred during this period. It was the second geologic
Geology

Geology is the science and study of the solid and liquid matter that constitute the Earth. The field of geology encompasses the study of the composition, structural geology, physical properties, dynamics, and History of the Earth of Earth materials, and the processes by which they are formed, moved, and changed....
 period of the Neoproterozoic
Neoproterozoic

The Neoproterozoic Era is the unit of geologic time scale from 1,000 to 542 +/- 0.3 million years ago. The terminal Era of the formal Proterozoic Eon , it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods....
 Era, preceded by the Tonian
Tonian

The Tonian is the first geologic geologic period in the Neoproterozoic era and lasted from 1000 annum to 850 Ma . Instead of being based on stratigraphy, these dates are defined by the International Commission on Stratigraphy based on radiometric dating....
 Period and followed by the Ediacaran
Ediacaran

The Ediacaran Period is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon....
. These so-called 'snowball earth
Snowball Earth

Snowball Earth refers to hypotheses regarding paleoclimate global-scale glaciation, claiming that the Earth's surface was nearly or entirely frozen at some points in its past....
' events are the subject of much scientific controversy. The main debate involves whether these glaciations were truly global or merely localised events.

The period has not received the international ratification that all geological time periods undergo (the most recent being the Ediacaran
Ediacaran

The Ediacaran Period is the last geological period of the Neoproterozoic Era and of the Proterozoic Eon, immediately preceding the Cambrian Period, the first period of the Paleozoic Era and of the Phanerozoic Eon....
 Period, which was ratified in 2004). The period is defined only on the dates of the rocks and no observable and documented systematic global event. This is problematic as estimates of rock dates are variable and are subject to laboratory error. For instance, the Cambrian
Cambrian

The Cambrian is a geologic period that began about Mya at the end of the Proterozoic eon and ended about Ma with the beginning of the Ordovician period ....
 Period is marked not by rock younger than a given age ( million years), but by the appearance of the world wide Trichophycus pedum
Trichophycus pedum

Trichophycus pedum is regarded as the earliest widespread complex trace fossil. Its earliest appearance, which was contemporaneous with the last of the Ediacaran biota, is used to define the dividing line between the Ediacaran and Cambrian Period ....
 trace fossil assemblage. This means that rocks can be recognised as Cambrian when examined in the field and do not require extensive testing to be performed in a lab to find a date. As yet, there is no consensus on what global event is a suitable candidate to mark the start of the Cryogenian period, and its base is only loosely set to Ma.

The name refers to the very cold global climate of the Cryogenian: characteristic glacial deposits indicate that Earth
Earth

Earth is the third planet from the Sun. Earth is the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is also referred to as the World and Wiktionary:Terra.Note that by International Astronomical Union convention, the term "Terra" is used for naming extensive land masses, rather...
 suffered the most severe ice ages in its history during this period. Glacier
Glacier

A glacier is a large, slow-moving mass of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity and high pressure....
s extended and contracted in a series of rhythmic pulses, possibly reaching as far as the equator. It is generally considered to be divisible into at least two major worldwide glaciations. The Sturtian glaciation persisted from 750 million years ago to 700 Ma, and the Marinoan/Varanger glaciation terminated at circa 635 Ma. The deposits of glacial tillite also occur in places that were at low latitudes during the Cryogenian, a phenomenon which led to the hypothesis of deeply-frozen planetary oceans called "Snowball Earth
Snowball Earth

Snowball Earth refers to hypotheses regarding paleoclimate global-scale glaciation, claiming that the Earth's surface was nearly or entirely frozen at some points in its past....
".

During the Cryogenian, the supercontinent Rodinia
Rodinia

In geology, Rodinia is the name of a supercontinent, a continent which contained most or all of Earth's landmass. According to plate tectonic reconstructions, Rodinia existed between 1100 and 750 million years ago, in the Neoproterozoic era ....
 broke up, and the supercontinent Pannotia
Pannotia

Pannotia, first described by Ian W. D. Dalziel in 1997, is a hypothetical supercontinent that existed from the Pan-African orogeny about 600 million years ago to the end of the Precambrian about 540 million years ago....
 began to form.

Further reading