Before revision: Euxinic deep water is a key component of the Canfield ocean, a model of oceans during part of the Proterozoic period (a part specifically known as the Boring Billion) proposed by Donald Canfield, an American geologist, in 1998.
After revision: Euxinic deep water is a key component of the Canfield ocean, a model of oceans during part of the Proterozoic eon (a part specifically known as the Boring Billion) proposed by Donald Canfield, an American geologist, in 1998.