They can be identified through chemical proxies such as isotopes in sediment (*) cores, and organisms that lived during these time periods include ground sloths, saber-tooth cats, and mastodons.
One theory of these phenomena was developed by Karl Schimper and Louis Agassiz, whose work drew upon the ideas of Goethe and de Charpentier. The first of these events, probably triggered by the Great Oxygenation Event, was known as the Huronian, while the most recent one created many pluvial lakes. They can be identified through chemical proxies such as isotopes in sediment (*) cores, and organisms that lived during these time periods include ground sloths, saber-tooth cats, and mastodons. For ten points, identify these periods of long-term reduction in the Earth's surface temperature, which may have resulted in a Snowball Earth.
One theory of these phenomena was developed by Karl Schimper and Louis Agassiz, whose work drew upon the ideas of Goethe and de Charpentier.
{ice age}s (accept {glacial age}s and {glaciation}s)