[AS.] An outflow of water from the ground. The water of springs consists of rain-water which has soaked into the ground and percolated through the rocks, sometimes for a distance of several miles. Water easily passes through porous rocks, such as sandstone, but it cannot pass through clay. It then travels along the junction of two strata for a greater or less distance until it finds its way to an outlet and reappears at the surface as a spring. Springs of this simple character are very common, and are known as surface springs. An Intermittent Spring is one that flows and stops alternately being connected with a reservoir (b) by a sutured siphon (a). Mineral springs have mineral ingredients, which they hold in solution.