Crust (geology) centers, where partial-melting of the underlying mantle yields basaltic magmas and new ocean crust forms. This "ridge push" is one of the driving forces of plate tectonics, and it is constantly creating new ocean crust. That means that old crust must be destroyed somewhere, so, opposite a spreading center, there is usually a subduction zone: a trench where an ocean plate is being shoved back into the mantle. This constant process of creating new ocean crust and destroying old ocean crust means that the oldest ocean crust on Earth today is only about 200 million years old. In contrast, the
Women and the environment 1980s was an important decade for women in the environment. In 1980 the term 'ecofeminism' was born with two important events taking place. In April, 1980 the conference, "Women and Life on Earth: Ecofeminism in the 1980's" was held in Amherst, MA, the first in a series of conferences on ecofeminism. In November, 1980 the Women's Pentagon Action took place in Washington D.C.. when the group, "Women and Life on Earth" gathered to protest war, militarism, nuclear weapons and the effects on the environment. At its core, ecofeminism recognizes the link between the oppression of women and the oppression of