Eighteen Years in the Paraná: Explorations of Latin American Nature by Diego de Alvear y Ponce de Leon

Following the Treaty of Madrid (1750) a bilateral Boundary Demarcation Commission was established to negotiate a permanent Luso-Hispanic Boundary in Ibero-America. The division between Spanish and Portuguese America remained imprecise, metaphorically drawn through a wild hinterland characterized by impenetrability and seclusion. Owing to the lack of scientific observations, the Commission dispatched parties of geographers to survey the limits and study its environmental conditions. The career of one Spanish agent, Diego de Alvear y Ponce de Leon (1749-1830), illustrates the prolonged process of boundary demarcation and the extensive observations and measurements it produced. Although colonial agents and Jesuit priests traveled through Amazonia and the upper Paraná beginning in the sixteenth century, the indigenous populations and natural resources of these regions remained largely understudied. Simply put: what lay hidden within the imposing environment? Surveying efforts began in 1751 and stretched as late as 1801 in remote regions. The scope of the project strained imperial resources, but it also produced unprecedented European observations of some of the most remote environments in Ibero-America. Alvear’s eighteen-year survey of the Paraná and Paraguay river basins included cartographic surveys, natural historical writings, and proto-ethnographic reports. Drawing on Alvear’s diary from the survey and his published account of the region, this paper will examine Spanish conceptions of the Paraná as an extreme environment through the lens of environmental, political, and social history.