Caddo Parish, in the northwestern corner of Louisiana is bounded on the east by the present channel of Red River. In the vicinity of the Belcher Mound site (Fig. 2) this river follows the eastern escarpment of hills for about 15 miles, with all of its overflow valley lying to the west and varying in width from three miles at the upper part of this stretch to ten miles at the level of the site. The hills to the west of the valley are generally lower than the eastern escarpment and are cut through by several streams, including the Caddo Lake outlet, which follow the western valley margin to the Shreveport level, where they enter the river. The valley floor is covered by mixed red loam and sand, the characteristic overflow deposit of Red River. Along the channel sandy soils form elevated natural levees (“front lands”) so that the numerous small streams which traverse the valley floor have to flow downslope to the outlet of Caddo Lake. The western portion of the valley (“back lands”) was formerly covered by shallow lakes with a few islands of sandy loam. The soil of the old lake beds is a tight red clay containing numerous fragments of mussel shells; one of these lakes, Soda (originally Soto?) Lake, is shown in early maps to extend from the Caddo Lake outlet to the Shreveport level.