Paleolimnological and archaeological records that span 3500 years from Lake Titicaca and the surrounding Bolivian–Peruvian altiplano demonstrate that the emergence of agriculture (ca. 1500 B.C.) and the collapse of the Tiwanaku civilization (ca. A.D. 1100) coincided with periods of abrupt, profound climate change. The timing and magnitude of climate changes are inferred from stratigraphic evidence of lake-level variation recorded in14C-dated lake-sediment cores. Paleo-lake levels provide estimates of drainage basin water balance. Archaeological evidence establishes spatial and temporal patterns of agricultural field use and abandonment. Prior to 1500 B.C., aridity in the altiplano precluded intensive agriculture. During a wetter period from 1500 B.C. to A.D. 1100, the Tiwanaku civilization and its immediate predecessors developed specialized agricultural methods that stimulated population growth and sustained large human settlements. A prolonged drier period (ca. A.D. 1100–1400) caused declining agricultural production, field abandonment, and cultural collapse.

Ternary and quaternary bulk amorphous Pd-Ni-P and Pd-Ni-Fe-P alloys were prepared by fast quenching in water. X-ray photoemission spectra of Pd-Ni-P have previously been measured by Alamgir et al. (Phil. Mag. B 79, 239 (1999)). These results have been extended by (a) measuring the Auger spectra and the Auger parameters of key elements, (b) cross correlating the data with PdNi binaries, and (c) investigating the effects of adding Fe. It is shown that the Auger parameters change systematically across the composition range and the results are discussed in terms of possible charge transfer, changes in d-band character, and covalent bonding.

In Inka mythology, a large sandstone rock on the Island of the Sun, in Lake Titicaca, was the origin place of the sun. It was there that the sun first emerged and designated the Inka as his children. Under Inka rule, and perhaps before, this rock was a destination of pilgrims who went to worship and make offerings to the sun. We present evidence that a set of solar markers existed on a ridge northwest of the sacred rock. These structures framed the sunset for groups of watchers on the June solstice, near the time of the sun festival, Inti Raymi. Historic information coupled with the organization of archaeological sites within the sanctuary area on the island suggests that elites and common pilgrims may have observed the sunset from different locations.