Environmental change and economic development in coastal Peru between 5,800 and 3,600 years ago Daniel H. Sandweissa,1, Ruth Shady Solísb, Michael E. Moseleyc,1, David K. Keeferd, and Charles R. Ortloffe aDepartment of Anthropology/Climate Change Institute, 120 Alumni Hall, University of Maine, Orono, ME 04469; bProyecto Especial Arqueolo´gico Caral-Supe, Avenida Las Lomas de la Molina 327, Urb. Las Lomas, Lima 12, Peru; cDepartment of Anthropology, University of Florida, Gainesville, FL 32611; dClimate Change Institute, Bryand Global Sciences Center, University of Maine, Orono, ME 04469; and eCFD Consultants International, Ltd., 18300 Southview Avenue, Suite 2, Los Gatos, CA 95033-8537 Contributed by Michael E. Moseley, December 11, 2008 (sent for review October 10, 2008) Between Ϸ5,800 and 3,600 cal B.P. the biggest architectural mon- scape, transporting massive quantities of the loose sediment into uments and largest settlements in the Western Hemisphere flour- the rivers and down to the coast. ENSOs that follow large ished in the Supe Valley and adjacent desert drainages of the arid earthquakes move particularly large quantities of material. After Peruvian coast. Intensive net fishing, irrigated orchards, and fields initial delta formation and sediment spreading to form subsea of cotton with scant comestibles successfully sustained centuries of ridges composed of finer particles along the shoreline, normal increasingly complex societies that did not use ceramics or loom- longshore littoral processes further develop the sediment into based weaving. This unique socioeconomic adaptation was coast-parallel, linear beach ridges (9). Four decades of high- abruptly abandoned and gradually replaced by societies more altitude time-lapse images, spanning a major earthquake, 2 El reliant on food crops, pottery, and weaving. Here, we review Nin˜o flood events, beach ridge formation, and sand dune evidence and arguments for a severe cycle of natural disasters— incursion have revealed these processes in action during the 20th earthquakes, El Nin˜o flooding, beach ridge formation, and sand century at the Santa River (9° S) (8), demonstrating that dune incursion—at Ϸ3,800 B.P. and hypothesize that ensuing transport of massive quantities of sediment to the coast leads to physical changes to marine and terrestrial environments contrib- beach ridge formation and ultimately to episodic sand dune uted to the demise of early Supe settlements. invasions of inland areas. This ridge-and-dune regime, and the earthquakes and floods that drive it, can have severe conse- ͉ ͉ ͉ El Nin˜o geoarchaeology Preceramic collapse Mid-Holocene quences for humans in this extreme desert environment. dapted to a coastal desert broken by verdant river valleys Early Disasters in Supe—Earthquakes, Floods, and Sand Aand fronted by a productive near-shore fishery, the north The north central coast is one of the most seismically active central coast of Peru was very different from other centers of regions on earth, with earthquakes produced by the subduction ancient development. Although characterized by complex social of the offshore Nasca Plate beneath the South American Plate. organization and large centers dominated by stone-faced temple Historically, large and great earthquakes [magnitude (M) Ͼ 7.5] mounds, early coastal Peruvians did not produce pottery or have occurred along this segment of the plate boundary approx- loom-woven cloth. Animal protein came entirely from the sea, imately twice every century on average (10), and similar occur- not from domesticated or terrestrial animals. Irrigated farming rence rates are expectable prehistorically. Damage of probable focused on cotton; among the remains of food crops are the tree earthquake origin is evident at a number of structures excavated fruits guayaba (Psidium guajava) and pacae (Inga feuillei), achira by Shady (1, 11, 12); here, we summarize the Late Preceramic (Canna edulis, a root crop), beans, squash, sweet potato, avo- cases of 2 platform mounds at 2 different Río Supe sites: one cado, and peanut. This unique evolutionary experiment thrived coastal (Aspero) and the other 23 km inland (Caral). The most Ϸ for 2 millennia (the Late Preceramic Period, ca. 5,800–3,800/ spectacular wreckage transpired during the penultimate use of 3,600 cal B.P.) in the Río Supe and adjacent desert drainages the Pira´mideMayor, the main temple platform at Caral, a 66-ha (1–3) (Fig. 1). Ending abruptly, this Late Preceramic society was interior monumental center. At the time of impact, the platform gradually replaced by more typical or normative economies that base measured Ϸ170 m by 150 m and rose in steps to a Ϸ19- to emphasized plant and animal domesticates while also producing 30-m-high flat summit covered by masonry walled courts, com- pottery and woven goods. partments, rooms, and corridors. Pervasive damage to almost all Eustatic sea level stabilization between 6,000 and 7,000 years summit structures, expressed in fallen, tilted, or offset walls and ago set the stage for the Late Preceramic developments, both displaced floors, is unusually well preserved because the wreck- natural and cultural. Rising sea level had inhibited the estab- age was not repaired but filled over during final use. In terms of lishment of sandy beaches, beach ridge formation, and conse- core damage, a large and deep-seated rotational landslide quent inland sand dune deposition while leading to the devel- displaced a huge volume of construction material in the south- opment of large, protected bays. When sea level transgression west quadrant of the temple itself. Near the summit of the ceased in the Mid-Holocene, this geophysical configuration changed significantly. Approximately 5,800 years ago, the return temple, structures were disturbed by back-rotational movement of El Nin˜o (the warm phase of the El Nin˜o–Southern Oscillation in the scarp area of the landslide block (Fig. 2), whereas low phenomenon, or ENSO) after a hiatus of several millennia (4, 5) down on the south face, the landslide caused a wide area of the GEOLOGY coincided with emplacement of the modern fishery dominated by small schooling fish (6, 7) and of the contemporary coastal Author contributions: D.H.S., M.E.M., D.K.K., and C.R.O. designed research; D.H.S., R.S.S., regime dominated by powerful north-flowing longshore currents M.E.M., D.K.K., and C.R.O. performed research; D.H.S., R.S.S., M.E.M., D.K.K., and C.R.O. and strong daily winds blowing inland NNE off the sea. Estab- analyzed data; and D.H.S., R.S.S., M.E.M., D.K.K., and C.R.O. wrote the paper. lishment of these conditions created the beach ridge and sand The authors declare no conflict of interest. dune geomorphic regime that has characterized the north coast 1To whom correspondence may be addressed. E-mail: [email protected] or of Peru since the Mid-Holocene (e.g., ref. 8). In this tectonically [email protected]fl.edu. active region, seismic activity produces abundant unconsolidated This article contains supporting information online at www.pnas.org/cgi/content/full/ 0812645106/DCSupplemental. sediment from earthquake-triggered landslides. Subsequent ANTHROPOLOGY ENSOs bring torrential rain to the vegetationless desert land- © 2009 by The National Academy of Sciences of the USA www.pnas.org͞cgi͞doi͞10.1073͞pnas.0812645106 PNAS ͉ February 3, 2009 ͉ vol. 106 ͉ no. 5 ͉ 1359–1363 Downloaded by guest on September 24, 2021 78˚ 72˚ 0˚ 0˚ Quito COLUMBIA Caqueta R. ECUADOR Japura R. Rio Napo Putumayo R. Pastaza R. Amazon Amazon Yavari R. Talara Chira Marañón R. Colán ridges ridges 6˚ Ucayali R. 6˚ Jurua R. Cajamarca Huaca Prieta Huallaga R. BRAZIL Marañón R. Santa Purus R. SOUTH ridges PACIFIC OCEAN North Ancón-Chillón Alto Purus R. Central Caral Coast Urubamba R. 12˚ Madre de Dios R. 12˚ Lima Llanos de Peru Mojos Cusco Beni R. International Boundary PERU Apurimac R. National Capital Archaeological Site BOLIVIA Major Cities Rivers Lake Titicaca 0 100 200 Kilometers 0 100 200 Miles La Paz 18˚ 18˚ Lake CHILE Poopo 78˚ 72˚ Fig. 1. Map showing location of Caral, north central coast, and major beach ridge sets in northern Peru. The Medio Mundo ridge is coincident with the North Central Coast, from 10.5 to 11.2 S latitude. pyramid to bulge outward. This bulge was evidently repaired, form (14) measured Ϸ40 ϫ 34 m at the base and was 10 m high and the face smoothed over when the summit damage was when it was affected or hit. Common people then settled atop the filled over. former temple and dumped substantial garbage on its unre- Landslides of this type can be triggered by a variety of causes, paired surface and sides. The masonry sides and fill exhibit but in this hyperarid environment core construction materials of fissures with displacements of as much as 15 cm, whereas the the Pira´mideMayor were presumably dry, implicating an earth- central ceremonial stairway suffered a large near-vertical crack quake trigger for this landslide-induced structural collapse. with several centimeters of lateral separation (Fig. 3). As at Landslides of the Caral type can occasionally be triggered by Caral, the most likely cause of this damage was seismic shaking. earthquakes of only moderate size, but they are typically trig- If the Late Preceramic damage at both sites was due to a single gered by the relatively severe and long-lasting ground shaking seismic event, then this was a relatively large earthquake, associated with large earthquakes (13) that are typical of the estimated at M Ն 7.2 [see supporting information (SI) Text], as subduction zone along Supe region coastline (10). is typical of the subduction zone offshore (10). If 2 separate Highly probable earthquake damage also appears in at least 1 events were involved, the one damaging Caral was probably M of 6 mounds at the 19-ha coastal complex of Aspero.