Early Palaeozoic Icehouse
From Infogalactic: the planetary knowledge core
The Early Palaeozoic Icehouse was a cool period that interrupted the greenhouse temperatures of the Ordovician and Silurian periods, culminating in the Hirnantian glaciation and the Ordovician extinction event.[1] The icehouse was formerly thought only to consist of the Hirnantian glaciation itself, but has now been recognized as a longer, more gradual event.[2]
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