A panel written by Giovanni Gallo, in O Museu do Marajo, states: “On Marajo it is not the national president, nor the governor, that reigns. Here, there is an absolute and total dictatorship: water. It is water that offers the means of subsistence and impedes life; it conditions health, work, everything, without raising its voice in a disloyal, ruthless way. The seasons of the year have but one name: water, mud, drought. It is the dictatorship of water.”
Marajo Island, 49,606km2 in area, is the largest and easternmost island in an archipelago that lies at the mouth of the Amazon River. The enormous amount of nutrient-laden sediment carried by this powerful river and deposited on the western portion of Marajo and on several smaller islands (covered with terra firme forest, floodplain forest, and flooded forests) annually renews the soil, allowing relatively productive agriculture (Figure 19.2). In contrast, the eastern part of Marajo Island has a greatly reduced rate of sedimentation and does not benefit from the Amazon River sediments and their nutrients. The low savannas here are characterized by heavy clay and impermeable soils and are covered with grass and shrubs.
Figure 19.2. Vegetation patterns, sites, and towns on northeastern Marajo Island. (Denise Schaan)
The climate is characterized by a rainy season that runs from January until June. Virtually all of the annual precipitation (2,800-3,600 mm) falls during these six months making the rivers on Marajo Island seasonal. The drainage system is handicapped by the virtually flat topography and impermanent nature of most of the rivers. Moreover, several portions of the island lie below sea level. The savannas of Marajo can be compared (as Ackermann 1963 has suggested) to a flat plate with rising edges; it holds 1-2 m of rain water in 70% of its area for half of the year. The archaeological mounds are among the few patches of land that remain dry and visible in this shallow body of water.
The dry season is first felt in early July, but it is August that marks a transitional month when the waters have receded enough to expose most of the land, now covered with mud. From September to December, trade winds help to dry the soil and also carry away the rain clouds making precipitation virtually absent during these summer months. The heavy clay soils bake and crack under the equatorial sun, forming the so-called terroadas - an uneven, desiccated terrain covered with sparse grass. As the season advances, the grass turns brown and burns from natural and human induced fires.
The present economy is based on cattle and buffalo ranching, as well as the exploitation of natural resources such as timber and palms. Fishing is the second most important economic activity, especially on the savannas and along the eastern coast, where floating meadows and mangroves provide important food resources for fish populations (Smith 2002). Agricultural productivity is limited by nutrient-poor, impermeable soils, and an imperfect drainage system (OEA 1974; Sioli 1984; Sombroek 1966). Agriculture has been unsuccessful even in the area of transition between the savannas and forest (Murrieta, Dufour and Siqueira 1999) or along the coast, where it is limited to small-scale cultivation of pineapple and manioc.
Changes in the availability of resources, work schedules, and ease of movement caused by the seasonal floods and droughts have amazed both natural scientists and novelists dedicated to understanding and reporting on the native way of life on the largest island of the estuary. Archaeologists, however, have not paid enough attention to the immense limitations imposed by ecology to subsistence choices and settlement locations, and particularly the stimulus that ecology has provided to the development of landscape management practices during pre-Columbian times.
During the dry season, when small streams cease to flow and small lakes dry up, ranchers dam rivers and excavate ponds (the so-called rampas) to retain water for livestock.
At the end of the rainy season, fishermen who live along the main rivers travel to the headwaters, where dams and enclosures (corrals) retain fish that spawn in the flooded savannas during the rainy season and head back to the main rivers when the waters recede. All over the savannas, large amounts of fish are trapped in deeper bodies of water and small impermanent streams. Fish are then mass harvested for weeks to come, providing plenty for local consumption and sale. The exceptional fish productivity of Marajo’s savanna lakes and rivers has been reported since early colonial times, when the island supplied the recently founded city of Belem, located just across the bay, with tons of fish, turtles, turtle butter, and other products (Furtado, Lima, Albuquerque, and Castro 2002). Archaeologists have not considered the fact that the archaeological sites are located exactly in areas of high fish productivity, and that earthen mounds were only part of a wider range of earthworks designed to manage aquatic fauna.
It should be acknowledged, however, that previous research has occasionally referred to unusual landscape features, such as excavations next to the mounds, or to the fact that some mounds were partially built inside the adjacent river (Derby 1879; Roosevelt 1991:
31,168; Simoes and Figueiredo 1964). It was not realized, however, that such excavations were ancient ponds, and that earthen structures connected to mounds were remains of prehistoric dams.
Visiting the upper Anajas River in the dry season, one will observe a huge shallow lake formed right in front of the Monte Carmelo and Guajara mounds. That lake provides abundant fish for regional consumption and sale thanks to a dam that is annually rebuilt adjacent to the mounds. Such practices, facilitated by local ecology, are very common elsewhere in the savannas. There is mounting evidence that they were first employed during pre-Columbian times.
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