of Hispanic America. Grass and water are to be had at marshy spots at the foot of headwater scarps, and every one of these green patches is known to men who follow the trails. As the contours on the Iquique sheet plainly show, there is a flat tabular element in the relief of the crest of the cordillera that continues all the way from the Cordillera Sillilica, a little south of latitude 20° S., southward through the entire sheet and even into the Atacama sheet beyond. These flat tabular masses are separated by very deep and steep-sided ravines and canyons, which are completely hidden if one stands upon the summit of one of the plateau-like tracts and looks lengthwise along the range. So conspicuous are the tabular masses and so different from the general character of the peaks east of them that form clusters and ranges upon the watershed that they have been given specific names. For example on the northern border of the Iquique sheet in longitude 69° and almost due east of Iquique are the ‘Altos de Sitilca,’’ south of them the “Altos de Pica,”’ both of which exceed 4000 meters (13,000 feet) in elevation, South of Calama are similar masses, most of which are called “ cerros,’' the term being used not in the usual sense as indicating an isolated hill or hills but in the sense of elevated tracts of land crowned by isolated hills; and between these cerros are broad and rather flat high- level tracts whose borders are the gathering grounds of waste from the mountains, strewn in broad belts where the plain and the plateau meet. The latter are called “llanos.’’ Examples appear upon the Iquique sheet (about latitude 23° S., longi- tude 68° 30’ W.) in the “ Llano del Quimal”’ and the “ Llano de la Paciencia.’’ Between the Llano de la Paciencia and the Salar de Atacama there lies the Cerros de la Sal. The latter again illustrates the tabular character of a great deal of the relief that constitutes the western flank and summit of the Western Cordillera. Seen from the eastern side of the Salar de Atacama the Cerros de la Sal has a strikingly even sky line. 1 have photographed it over a horizontal distance of fifteen or twenty miles and crossed it on the trail to Calama, where its complicated structure and its even top are in marked dis- cordance and indicate an old relief developed at a lower level
