General Gregory J. Arigma A.E. Arigma in the Plateau Regim of horizontal strata Central Regim (going from N.W.-to S.E.) in the Mountain Regim of sierras with filled in valleys between. The Regim is from 70 to 100 miles and all of the strata are folded. Their trend is "nearly north- north east and south east, but near the Mexican border it becomes more nearly north and south, and the mountain gne as north side eralesces with a belt of north-south ranges which extends northward through New Mexico and divides the Plateau Regim in the east. The northwesting belt of Arigma is described by Seltut as continuous with the Basin Range system of Nevada and Utah, and is considered by him as exhibiting the same prevailing type of geographic structure. He states that his examination "have demonstrated no anticlinal structures, except as minor features. The usual structure is monoclinol demonstrative due to faulting in the Chiricahua and Pinal ranges, and presumably so in many others." With this conclusion the observations em- bodied in the present folio accord? (1).