Definitions for erathem
erath·em

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1. Erathem

   In stratigraphy, paleontology, geology, and geobiology an erathem is the total stratigraphic unit deposited during a certain corresponding span of time during an era in the geologic timescale. It can therefore be used as a chronostratigraphic unit of time which delineates a large span of years – less than a geological eon, but greater than its successively smaller and more refined subdivisions (geologic periods, epochs, and geologic ages). By 3,500 million years ago (mya) simple life had developed on earth (the oldest known microbial fossils in Australia are dated to this figure). The atmosphere was a mix of noxious and poisonous gases (Methane, Ammonia, Sulphur compounds, etc. – a so-called reducing atmosphere lacking much free oxygen which was bound up in compounds). These simple organisms, Cyanobacteria ruled the still cooling earth for approximately a thousand million (over a billion) years and gradually transformed the atmosphere to one containing free oxygen. These changes, along with tectonic activity left chemical trails (red bed formation, etc.) and other physical clues (magnetic orientation, layer formation factors) in the rock record, and it is these changes along with the later richer fossil record which specialists use to demarcate times early in planet earth's history in various disciplines. Erathems are not often used in practice. While they are subdivisions of eonothems and are themselves subdivided into systems, dating experts prefer the finer resolution of smaller spans of time when evaluating strata. Erathems have the same names as their corresponding eras. The Phanerozoic eonothem can thus be divided into a Cenozoic, a Mesozoic and a Paleozoic erathem or matching era name.Similarly, the Proterozoic eonothem is divided youngest to oldest into the Neoproterozoic, Mesoproterozoic and Paleoproterozoic erathems, and the Archean eon and eonothem are divided similarly into the Neoarchean, Mesoarchean, Paleoarchean and the Eoarchean, for which a lower (oldest) limit is undefined.

How to pronounce erathem?

1. Alex

   US English

   David

   US English

   Mark

   US English

   Daniel

   British

   Libby

   British

   Mia

   British

   Karen

   Australian

   Hayley

   Australian

   Natasha

   Australian

   Veena

   Indian

   Priya

   Indian

   Neerja

   Indian

   Zira

   US English

   Oliver

   British

   Wendy

   British

   Fred

   US English

   Tessa

   South African

How to say erathem in sign language?

Numerology

1. Chaldean Numerology

   The numerical value of erathem in Chaldean Numerology is: 8

2. Pythagorean Numerology

   The numerical value of erathem in Pythagorean Numerology is: 7

References

1. ^ Wikipedia
   https://en.wikipedia.org/wiki/Erathem