The SGZ is distinguished primarily on the basis of vegetation, and especially by a cover of very dense bunch grasses. These grasses include cachu-ch'iji (Muhlenbergia fastigiata, Paspolum pygmaeum), orko-ch'iji (Distichlis humilis), ch'iji (Boutelova simplex), and yawara (Nasella spp.) ([Albarracín-Jordan 1996a]: 13). This zone also frequently includes swampy areas - pantanales or bofedales - which are formed by the presence of numerous springs and poor drainage conditions. These areas include more a variety of other plants, many of which are useful as fodder for livestock, as well as abundant and varied avian life.
The soils of the SGZ are well-developed and deep. A thick humus and root zone is common, and the texture at times approaches peat. Indeed, the ground often has a ``springy'' texture when walked across. Geologically, this zone sites atop deep quaternary lacustrine deposits.
As is evident from Figure 2.1, most of the sites in the SGZ are located below 3820 m.a.s.l. The few exceptions are located in the bottoms of quebradas or in one of the major inland valleys of the peninsula. These areas have similar soils and vegetative communities to those of the lake plain which in fact makes up most of the area of the SGZ.
The heavy soils of the SGZ made it difficult to work with traditional Andean agricultural tools, and, indeed, with the introduced oxen-plow as well. Recently, however, tractors have arrived in the altiplano, and the SGZ has been brought under production in a significant way. Mostly introduced cereals are planted in the lake plain. The Andean tubers are still planted mainly in the LCZ. As I mentioned above, the lake plain is more prone to frost than are the lower slopes of the hills, and this may be a factor, especially since the introduced cereals are usually grown for cash sale, while the tubers are intended at least in part for the sustenance of the cultivating household itself.