The precise mechanism involved in the formation of cap carbonates is not clear .
The most cited explanation suggests that at the melting of a snowball Earth , water would dissolve the abundant CO from the atmosphere to form carbonic acid , which would fall as acid rain .
The precise mechanism involved in the formation of cap carbonates is not clear , but the most cited explanation suggests that at the melting of a snowball Earth , water would dissolve the abundant CO from the atmosphere to form carbonic acid , which would fall as acid rain .