Early Settlement and Subsistence in the Casma Valley, Peru

1. Introduction

I Introduction Our interest in the Casma Valley dates from 1974 when, inspired by the descriptions ofTello (1956) and Kosok (1965), we first visited the valley. Until 1979, our visits were sporadic-accomplished at free moments during our investigations of the Moche Valley to the north. In 1979 and 1980, funding provided by the O'Neil and Netting Funds ofCarnegie Museum of Natural History made it possible for us to carry out surveys and test excavations at selected sites within and near the Casma Valley. This publication presents the preliminary results ofthose 1979 and 1980 investigations . Once all data have been more thoroughly analyzed and evaluated , a final report will be prepared. ENVIRONMENTAL SETTING The Peruvian coast is one of the driest deserts in the world. Rain is scarce because of the cold Peruvian or Humboldt Current that flows south to north from northern Chile to northern Peru. The cold waters of this current keep the air over the ocean cold and hold evaporation to a minimum. As the air moves inland, it is warmed and its capacity to hold water is increased, but rain does not fall until the air reaches the cooler elevations of the Andes at altitudes above 2,500 meters. Although the coast is kept arid by the Peruvian Current, it is also blessed with the richest oceanic biomass in the world. The continuous upwelling of nutrient-rich cold waters from depths below supports a tremendous food chain of plankton, shellfish, fish, seabirds, and sea mammals . These marine resources played a vital part in the development of coastal Andean civilization and are still important today. A few times every century, a large portion of the cold Peruvian Current is temporarily displaced by the warm Ecuadorian Countercurrent, resulting in a phenomenon called EI Nino. When a severe EI Nino occurs , as it did in 1925 and 1983, the marine food chain is affected, and 2 INTRODUCTION torrential rains drench the coastal desert. These effects occur in decreasing intensity toward the south, depending on the magnitude of the EI Nino phenomenon. By the time of the earliest occupation of the sites dealt with in this study (after 3000 B.C.), both climate and sea level had stabilized and were close to modern conditions (Craig and Psuty 1968; Osborn 1977; Parsons 1970). Therefore, the general conditions described above for contemporary Peru are applicable to the periods of cultural development we have chosen to investigate. The Casma Valley, one of fifty-seven river valleys that cross the Peruvian desert coast, is located on the north-central coast some 350 kilometers north of Lima (fig. I). The valley (fig. 2) actually consists of two rivers, the Sechin branch on the north and the Casma branch on the south, which meet to form the Casma River some 10 kilometers from the Pacific Ocean. The total drainage basin is 2,775 square kilometers, but like most Peruvian coastal rivers, the Casma River is characterized by marked seasonal variation in river flow. The peak flow period, December to April, has monthly runoff rates up to 89 cubic meters per second (ONERN 1972: 31, 290). Since rain almost never falls on the Peruvian coast, all agriculture is dependent on canal irrigation, making river flow extremely important. Both branches of the Casma Valley are bordered by steep mountains and are rather narrow, varying from 1.5 to 2 kilometers wide, until they join to form the Casma Valley proper. Near this junction, the surrounding mountains become smallerfoothills, often interspersed with stretches of desert sands, and the Casma Valley widens to 7 kilometers near its mouth. Within a few kilometers of the area of the mouth, land is only a few meters above sea level and is often too salty for agricultural purposes. PROJECT OBJECTIVES General surveys had already been done in the lower Casma Valley by Collier (1962) and Thompson (1961, 1962a, 1964a, 1974), and well upvalley within the Sechin branch of the Casma Valley by Fung and Williams (1977). Since our previous investigations in the Moche Valley at early sites had yielded important new findings (5. Pozorski 1976, 1979; S. Pozorski and T. Pozorski 1979a, 1979b; T. Pozorski 1975, 1976), and since the Casma Valley contains the largest concentration of Cotton Preceramic , Initial Period, and Early Horizon sites along the north and central Peruvian coast, we felt our best potential for contribution would Project Objectives 3 MOCHE NEPENA CULEBRAS Pacific Ocean HUARMEY PATIVILCA...