"... possibly turning into a giant ball of ice, with an almost entirely frozen surface. Very little is currently known about how this "snowball Earth" formed, or how life managed to cling on."
It's got some strong evidence. The drop-stones alone are a humdinger!
As for how, it's not hard to imagine the bulk of atmospheric carbon, pre-snowball, ending up at the bottom of the oceans. There wasn't any plants on land, so no chance of circulating through fires. And with very little animal life to produce CO2, that left volcanoes as the only source of CO2. Algae had free rein to clean the atmosphere spotless.
And once the snowball formed, the algae mostly dies off and the volcanoes slowly recover the CO2 levels until the ice suddenly melts in a strong positive feedback. The high atmospheric CO2 level now creates intense acid rain until the CO2 level can be brought back down.
Possibly? (Score:5, Interesting)
"... possibly turning into a giant ball of ice, with an almost entirely frozen surface. Very little is currently known about how this "snowball Earth" formed, or how life managed to cling on."
It's got some strong evidence. The drop-stones alone are a humdinger!
As for how, it's not hard to imagine the bulk of atmospheric carbon, pre-snowball, ending up at the bottom of the oceans. There wasn't any plants on land, so no chance of circulating through fires. And with very little animal life to produce CO2, that left volcanoes as the only source of CO2. Algae had free rein to clean the atmosphere spotless.
And once the snowball formed, the algae mostly dies off and the volcanoes slowly recover the CO2 levels until the ice suddenly melts in a strong positive feedback. The high atmospheric CO2 level now creates intense acid rain until the CO2 level can be brought back down.
Result is prolonged dissolution of rock.