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The glaciations were probably triggered by the Great Oxygenation Event (GOE), which removed atmospheric methane (a greenhouse gas), and eventually supplied free oxygen to the atmosphere. The alternate warm and ice age periods was probably caused by a repeating cycle. Cyanobacteria flourished in the warm periods, producing huge amounts of oxygen. The oxygen removed the free methane, and used up carbon dioxide. This caused the temperature to crash. This slowed down the bacteria. So the temperature rose again.
- Lane, Nick (2010). "First breath: Earth's billion-year struggle for oxygen". New Scientist (2746). https://www.newscientist.com/article/mg20527461.100-first-breath-earths-billionyear-struggle-for-oxygen.html. A snowball period, c2.4–c2.0 billion years ago, triggered by the Great Oxygenation Event  Archived 2011-01-06 at the Wayback Machine
- Williams G.E. & Schmidt P.W. (1997). "Paleomagnetism of the Paleoproterozoic Gowganda and Lorrain formations, Ontario: low palaeolatitude for Huronian glaciation" (PDF). EPSL 153 (3): 157–169. . http://www.cosis.net/abstracts/EAE03/08262/EAE03-J-08262.pdf.
- Evans D.A; Beukes N.J. & Kirschvink J.L. (1997). "Low-latitude glaciation in the Palaeoproterozoic era". Nature 386 (6622): 262–6. . http://www.nature.com/nature/journal/v386/n6622/abs/386262a0.html.
- Robert E. Kopp (2005). "The Paleoproterozoic snowball Earth: a climate disaster triggered by the evolution of oxygenic photosynthesis". Proc. Natl. Acad. Sci. U.S.A. 102 (32): 11131–6. . . . http://www.pnas.org/cgi/reprint/0504878102v1.