The Houston District, as the term is used in this paper, comprises an area between the Trinity and Brazos rivers in Harris County and parts of Montgomery, Waller, and Fort Bend counties, Texas. It consists of a plain of low relief that lies not far above sea‐level, and is a part of the West Gulf Coastal Plain. A part of the District is shown in Figure 1.

Large quantities of ground‐water are pumped in the Houston District from a succession of beds of sand that occur between 300 and 1,900 feet below the surface. These sands are interbedded with relatively impermeable clays. The formations range in age from Miocene to Recent and were deposited during several cycles of marine and continental deposition. They may be classified into several zones which are predominantly clay or predominantly sand, but in which the individual beds at most horizons can not be traced very far. Most of the beds interfinger and grade into one another laterally and vertically in short distances, the thinner beds in many places changing character or pinching out within a few hundred feet. The formations dip to the southeastward, the dip ranging from about 35 feet to the mile in the older formations to about 20 feet to the mile in the younger. In the outcrop‐areas of the formations, and for considerable distances down the dip, the sediments are in general dominantly sandy. Far to the southeastward, in the direction of the Gulf, clay predominates.