Page:Isaiah Bowman - Desert Trails of Atacama (1924).pdf/222



From my field journal are the following notes on the region. At Rosario de Lerma, the railway terminal, | met my pack train, and soon after starting we crossed the dry stream bed of the Rio Manzano (PIL. 2, p. 192). We passed ranch houses and irrigated alfalfa fields with orchards. In the late afternoon we ascended the Escoipe ravine. We camped on the middle slopes where a fairly heavy growth of scrub occurs and from turns in the trail had a view out over the irrigated land at the south of the mountains. The water of a half-dozen moun- tain streams is diverted through more than a score of main irrigating channels that make the valley green with corn and alfalfa. Within the mountains the principal valleys and the gentler lower slopes are covered with grainfields, chiefly barley and wheat, up to the edge of the broken land and to the limits of cultivation. From this point the trail climbs into the higher and rougher country of the Cuesta del Obispo and neighboring ridges that lie between Rosario de Lerma and Poma. Beyond these the descent begins; but it is gentle, and after passing the - small Sierra de Tintin and other lesser topographic elevations one comes into the broad and semiarid Calchaquf valley. In the southeastern corner of the Rosario de Lerma sheet (PI. 2) may be seen the flatter slopes of the alluvium-covered floor and the pattern of the irrigated tracts. Here and there are bits of better-watered ground with pasture. But for the most part the dry and gravelly alluvium has only scattered bunch grass and cactus.

On reaching the irrigated portions of the Calchaqui valley there is spread out before one a charming view of mountain and valley floor. From Palermo up valley there are scattered corrals and ranch houses and patches of green that mark the exit of mountain streams which here rise in the zone of clouds at the edge of the Puna de Atacama and sweep down to the alluvial lands where they nourish the fields (Fig. 64). Both the main stream and its tributaries have cut their channels below the general level of the valley floor so that steep banks of earth run for long distances parallel to the stream. But