View PDF. Here in Township 1 south and extending from Range 34 east to the edge of Range 36 east we concentrated our efforts. Between the towns of Clovis and Portales, a distance of about eighteen miles by the highway and running in a general east-southeast direction are a series of shallow dry basins, resembling old lake beds, which may be the remnants of a once larger drainage system. Udden 21 points out that the Brazos River once headed in the eastern flanks of the New Mexico Mountains.
This topography is quite different from that just described along the Guadalupe Mountains. About seven miles south of Clovis on the highway to Portales one comes to sand dunes above a depression, which deepens somewhat as one proceeds towards Portales, and which locally is known as Black Water Draw. In places it is hard to distinguish it from the level land of the Llano Estacado. No water stands at the surface, except in one or two places near its western end, and again near the Texas line to the east, where springs feed several very shallow alkaline lakes.
The headwaters of the Brazos River are not far away in Texas, and this, and other more or less parallel depressions between Clovis and Portales, may well represent a tributary of that river when it was fed by a much greater rainfall than is now found there.
All the evidence points to a former period of greater precipitation than the present, and a more or less gradual drying up, during the process forming a chain of shallow lakes that in the course of time became water-holes and finally dried up altogether, probably before any white settlers arrived on the scene.
Since the drying-up process of these basins, many of them have undergone erosion, chiefly by the wind, which has whipped up the sand into dunes, mostly along the north-east borders.
