Spring, a natural flow of water issuing at the surface of the earth. A spring occurs where underground water held in porous rock, called an aquifer, discharges at the surface through a natural opening, usually on a hillside slope.
Like the members of an ill-fated rock group, the seven continents struck out on their own hundreds of millions of years ago. But what caused the breakup? And is a reunion tour in the works? See more »