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The archaeological site of Quebrada Tacahuay, Peru, dates to 12,700 to 12,500 calibrated years before the present (10,770 to 10,530 carbon-14 years before the present). It contains some of the oldest evidence of maritime-based economic activity in the New World. Recovered materials include a hearth, lithic cutting tools and flakes, and abundant processed marine fauna, primarily seabirds and fish. Sediments below and above the occupation layer were probably generated by El Nino events, indicating that El Nino was active during the Pleistocene as well as during the early and middle Holocene.

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Before the Inca reigned, two empires held sway over the central Andes from anno Domini 600 to 1000: the Wari empire to the north ruled much of Peru, and Tiwanaku to the south reigned in Bolivia. Face-to-face contact came when both colonized the Moquegua Valley sierra in southern Peru. The state-sponsored Wari incursion, described here, entailed large-scale agrarian reclamation to sustain the occupation of two hills and the adjacent high mesa of Cerro Baúl. Monumental buildings were erected atop the mesa to serve an embassy-like delegation of nobles and attendant personnel that endured for centuries. Final evacuation of the Baúl enclave was accompanied by elaborate ceremonies with brewing, drinking, feasting, vessel smashing, and building burning.

Of the many canal systems of the Chimu empire the Chicama-Moche Intervalley (La Cumbre) Canal connecting the Chicama and Moche valleys represents the highest level of technical achievement. This paper examines the engineering skills of the Chimu as revealed by computer analysis of the open channel flow design techniques they utilized. Analysis of agricultural strategies made possible by this canal and the surveying skills inherent to its use are examined in detail. The presence of many trial canal paths toward the distal end of the canal indicate extreme difficulty in overcoming tectonically induced ground-slope changes caused by fault lines near the intervalley divide. The canal was abandoned prior to completion of construction and thus never served to supply the Moche Valley with Chicama water.

Between Ϸ5,800 and 3,600 cal B.P. the biggest architectural monuments and largest settlements in the Western Hemisphere flourished in the Supe Valley and adjacent desert drainages of the arid Peruvian coast. Intensive net fishing, irrigated orchards, and fields of cotton with scant comestibles successfully sustained centuries of increasingly complex societies that did not use ceramics or loombased weaving. This unique socioeconomic adaptation was abruptly abandoned and gradually replaced by societies more reliant on food crops, pottery, and weaving. Here, we review evidence and arguments for a severe cycle of natural disastersearthquakes, El Niñ o flooding, beach ridge formation, and sand dune incursion-at Ϸ3,800 B.P. and hypothesize that ensuing physical changes to marine and terrestrial environments contributed to the demise of early Supe settlements.El Niñ o ͉ geoarchaeology ͉ Preceramic collapse ͉ Mid-Holocene A dapted to a coastal desert broken by verdant river valleys and fronted by a productive near-shore fishery, the north central coast of Peru was very different from other centers of ancient development. Although characterized by complex social organization and large centers dominated by stone-faced temple mounds, early coastal Peruvians did not produce pottery or loom-woven cloth. Animal protein came entirely from the sea, not from domesticated or terrestrial animals. Irrigated farming focused on cotton; among the remains of food crops are the tree fruits guayaba (Psidium guajava) and pacae (Inga feuillei), achira (Canna edulis, a root crop), beans, squash, sweet potato, avocado, and peanut. This unique evolutionary experiment thrived for Ϸ2 millennia (the Late Preceramic Period, ca. 5,800-3,800/ 3,600 cal B.P.) in the Río Supe and adjacent desert drainages (1-3) (Fig. 1). Ending abruptly, this Late Preceramic society was gradually replaced by more typical or normative economies that emphasized plant and animal domesticates while also producing pottery and woven goods.Eustatic sea level stabilization between 6,000 and 7,000 years ago set the stage for the Late Preceramic developments, both natural and cultural. Rising sea level had inhibited the establishment of sandy beaches, beach ridge formation, and consequent inland sand dune deposition while leading to the development of large, protected bays. When sea level transgression ceased in the Mid-Holocene, this geophysical configuration changed significantly. Approximately 5,800 years ago, the return of El Niño (the warm phase of the El Niño-Southern Oscillation phenomenon, or ENSO) after a hiatus of several millennia (4, 5) coincided with emplacement of the modern fishery dominated by small schooling fish (6, 7) and of the contemporary coastal regime dominated by powerful north-flowing longshore currents and strong daily winds blowing inland NNE off the sea. Establishment of these conditions created the beach ridge and sand dune geomorphic regime that has characterized the north coast of Peru since the Mid-Holocene (e.g., ref. 8). In this tectonically ...

Mud bricks in Huaca del Sol and Huaca de la Luna differ in soil composition, dimensions, mold marks, and makers' marks. The differences reflect conditions of brick production and use, and some variables are chronologically significant. This paper discusses the archaeological significance of adobes in these platform mounds, located on the south side of the Moche Valley. Four brick variables-soil, dimensions, mold, and makers' marks-are examined in terms of patterns of associations.

T h e theory of plate tectonics contends that the continental plates occupied by humanity are in motion. T h e hypothesis of agrarian collapse (HAC) holds that gradual, as well as seismic, earth movement can induce ground slope change and modqy land-to-sea level relationships, thereby altering the distribution of surface and subsurface runoff, which can lead to abandonment of agricultural land. Mechanical principles underlying ongoing abandonment are detailed for large-scale imkation s y s t e m of the Andean Cordillera Negra. These principles are compatible with a historical scenario integrating urban development at pre-Hispaic Chan Chan, capital of the Chimor polity, with expansion, reform, and collapse of the city's agricultural hinterland. The applicability of the mechanics of agrarian collapse to two other centers of past civilization is briefly considered. [ agriculture, complex society, applied archeology, Peru] MICHAEL E. MOSELEY is Curator of Middle and South American Archeology and Ethnology. Field Museum of Natural History, Chicago, IL 60657. 773 774 AMERICAN A NTHR 0 POL OGIS T [85, 1983 The Andean SettizgThe Andean case study is focused on drainage and agriculture in the Pacific watershed of the Cordillera Negra of northern Peru between 6" and 9O south latitude (Figures 1 and 2). In this setting, ongoing landscape alteration is structured by extremes in physical conditions:1. Relative to its great height, the Andean Pacific watershed is one of the shortest and steepest in the world (Kosok 1965; Zeil 1979). Therefore, water flow responds rapidly and actively to small changes in ground slope or to changes in land-to-sea level relationships.2. The watershed is part of the leading edge of the westward-moving South AmericanPlate, and 150 to 200 km west of the coastline it collides with the Nazca Oceanic Plate, which is propelled eastward by high rates of sea floor spreading and underthrusts the Andean range at an average subduction rate of approximately 10 cm per year (Minster et al. 1974; Toksoz 1975). The oceanic plate passes less than 100 km beneath the Cordillera Negra, which has exhibited rates of gradual vertical oscillation averaging up to 1.8 cm per year, as well as large earthquakes (Wyss 1978). Therefore, the watershed is tectonically very active and the crustal blocks on which the landscape rides are in motion.3. The lower 40%-50% of the watershed lies within the world's driest desert (Lettau and Lettau 1978), and rainfall below approximately 2,000 m elevation occurs only in association with El Nzfio perturbations (Nials et al. 1979;Wooster 1980). These perturbations of normal marine and meteorological conditions can be predicted a year and a half in advance by the newly developed Ocean-Atmosphere paradigm (Wyrtki 1975;Cromie 1980;Gill 1982). The paradigm is also retrodictive and provides controls for holding late Holocene rainfall and climatic variability along the watershed as relative constants (Richardson 1981).These three extremes in physical conditions entail mechanical processes and c...