Three major glacial episodes(Ice-houses)

Polar Position Hypothesis: Glaciations occur when continents arelocated near the poles.

However:

Spreading Rate Hypothesis (BLAG)

BLAG Carbon Cycle

•On Land: CaSiO3 + CO2 -> CaCO3 + SiO2

•Subduction: CaCO3 + SiO2 -> CaSiO3 + CO2