ECOS Guide to the Ecology of the Northern Rockies
 
   
 

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Proterozoic Eon

2.5 billion – 543 million years ago (Proterozoic Eon)

During the ~billion years between 1.5 Ga and 800 Ma, a sea formed on the western margin of our present-day continent.  Huge amounts of sediment were deposited in this sea.  The sediments subsequently lithified into the red and green sandstone, mudstone, and limestone that are called the Belt formations (because they were first studied in the Belt Mountains).  The Belt formations contain remnants of algal life, but animals had not yet evolved.  The Belt formations are very abundant in western Montana; their localities are shown on this map. 


The "supercontinent" Rodinia
Illustration: Burke Museum
California and western Idaho had not formed by this time in Earth’s history.  North America was part of a larger ‘supercontinent’ called Rodinia, and western Montana was attached to some landmass that is now part of a different continent.  Towards the end of the Proterozoic Eon, the ‘supercontinent’ Rodinia broke apart.  Current research suggests that Siberia could be the landmass that was once connected to Montana.  The Udzha basin of Siberia might be the western half of Montana’s Belt basin. 

 

 
The ECOS program is sponsored by the University of Montana's Division of Biological Sciences, and the College of Forestry and Conservation. Carol Brewer Program Director, Division of Biological Sciences. Paul Alaback Program Co-Director, College of Forestry and Conservation.
NSF LogoECOS is supported by the GK-12 Program of the National Science Foundation.
Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the National Science Foundation.