1. Plural of isostacy; the state of equilibrium of the Earth's crust, in which the weight of continental and oceanic masses is balanced by the buoyancy of the underlying mantle.
Usage: geology; technical term; also spelled 'isostasies'

Examples

• The theory of isostacies explains why mountain ranges float on the mantle like icebergs on water.
• Geologists study isostacies to understand how continents maintain their vertical position over geological time.
• Isostacies principles help predict how the Earth's crust will respond to the removal of glacial ice sheets.
• The concept of isostacies was developed in the early 20th century to explain crustal stability.
• Different regions exhibit varying degrees of isostacies depending on their geological composition.