Limestone terracing, terra rosa soil, and fencing and watchtowers typical of the Central Hill Country In the hills, because the upper layers of limestone have many cracks and fissures, much of the winter rainwater seeps into the ground. It continues to seep down until it reaches an impermeable layer, where it begins to flow laterally. Eventually the water reaches the ground surface on the edge of a hillside or near the bottom of a valley where it flows out as a spring. At times, settlements developed