Relief shown by spot heights. Map on sheet 64 shows portion of Sonora. Photoimagery rectified by optical scanning from color infrared aerial photographs taken December 15, 1979 and July 22, 1982 by the Dirección General de Geografía del Territorio Nacional (DGGTN), Mexico D.F., Mexico. Each sheet includes quadrangle location map and diagr. of adjoining color image maps.