Spring lines form when water collects between a layer of permeable rock that rests on top of impermeable rock, forming springs. Towns and villages that settle along these water springs are called spring line settlements.
Early men chose to settle near water sources. Spring lines were ideal settlement locations, due to the available water supply. When villagers planted seeds, the water deposits helped promote crop growth.
The two kinds of rock create a constant water supply. Rainwater sinks through the shallow layer of permeable rock to an underground reservoir, where it collects on the impermeable rock. This supply of water, which may feed a spring, can be used to irrigate growing plants and crops.
Spring line settlements were often located at the base of a hill or escarpment, either along or not far from spring lines. Settlement away from spring lines, in drier areas such as grasslands or deserts, was uncommon.