Abstract
Historians claim that European colonizers of the northern coast of Rio de Janeiro State found vast herbaceous fields when arrived in this region. Hypotheses about the origin of these fields include forest burning by the Goitacás indians and periodical floods by the Paraíba do Sul River and the lagoon system. The palynologycal analysis of two lake cores obtained in the municipality of Campos dos Goytacazes revealed opening episodes of hygrophilous forest and the establishment of field vegetation, recorded at ca. 6,500 and ca. 4,000 (14)C yr BP. The partial replacement of forest by field vegetation in the first episode was probably caused by floods of the lower areas during the development of the Holocene lagoon phase. During the second episode, successions of vegetational patterns occurred due to lowering of the sea level. Drying and enlarging of the coastal plain have allowed its colonization by herbs and heliophyte plants. The palynological analysis does not provide any evidence that sustains the theories of use of fire and agricultural activities by indigenous groups during these periods.
Highlights
The geological features of the sea level oscillation during the Holocene in the coastal/deltaic plain of the Paraíba do Sul River, northern region of Rio de Janeiro State, were investigated by Martin et al (1984, 1993, 1997)
With the aim of reconstructing the temporal dynamics of the vegetation during the last 7,000 years, correlated to climatic changes and the sea level oscillation, palynological studies were performed on one core obtained in the Lagoa de Cima lake and on another in the Lagoa do Campelo lake, both located in the lowlands of the municipality of Campos dos Goytacazes
The analysis of the RJ93/1 core from the Lagoa de Cima lake can corroborate the results of Martin et al (1997), i.e. that the sea level before 7,000 yr BP (14C age) was probably lower than the current sea level, which was demonstrated by a sandy sequence in the lower part of the core and very low palynomorph concentrations
Summary
The geological features of the sea level oscillation during the Holocene in the coastal/deltaic plain of the Paraíba do Sul River, northern region of Rio de Janeiro State, were investigated by Martin et al (1984, 1993, 1997). This region presents several shallow lakes, isolated or not from the sea, being relict bays of a large palaeolagoon system. With the aim of reconstructing the temporal dynamics of the vegetation during the last 7,000 years, correlated to climatic changes and the sea level oscillation, palynological studies were performed on one core obtained in the Lagoa de Cima lake and on another in the Lagoa do Campelo lake, both located in the lowlands of the municipality of Campos dos Goytacazes. The investigation was established upon the data obtained from palynological analyses of sediments, considering the palynomorphs as pollen grains, spores of Pteridophyta and Bryophyta, zygospores and coenobia of Chloroccocales algae
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