RESUMO

Geoconservation has been growing in importance within the environmental management context. The conservation of geological heritage is being more and more recognised as an essential issue in nature conservation. Inventories of geosites are considered basic steps in geoconservation strategies and constitute a tool to support management considering the sites' values, use potential and risks of degradation. There are dozens of proposed methods to create inventories and to perform qualitative and quantitative evaluations of the sites and there are still discussions concerning the issues of how to select and evaluate sites and provide management guidelines. Geomorphosites are geosites with geomorphological nature and it is a category that presents some peculiarities highlighted in the literature. This work aimed at proposing a method for inventorying and assessing geomorphosites designed for territorial management focused on the use potential of the sites, divided into scientific, educational and geotouristic uses, the promotion conditions and the risks of degradation. The method was applied to the southeast coast of Rio de Janeiro State, Brazil, which has a high geomorphological diversity. The result was the creation of an inventory of geomorphosites in which all sites were described and quantitatively assessed, creating a product that can be easily applied in the management of the sites. The objective of this work was to contribute to the methodological discussions and to strengthen the insertion of geoconservation on territorial management.

Assuntos

RESUMO

Interpretation of sea-level indicators is essential when studying paleo sea-level fluctuations during the Holocene. Sea-level indicators may have different origins, such as geological (beachrocks) and biological (vermetids and barnacles). In order to reconstruct paleo sea-level, it is necessary to attribute an indicative meaning to each sea-level indicator. This paper aims to discuss issues raised by Angulo et al. (2016) regarding to the sea-level fluctuations curve proposed by Castro et al. (2014) to the Rio de Janeiro State coast, Brazilian southeast. The key issue that deserves posing is that local or regional curves cannot be built based on large scale (global) RSL geophysical models even in places of steady crust like Brazil. Here, we put into question the relative sea-level fluctuation curve model proposed by Angulo et al. (2006, 2016) to the coast of Rio de Janeiro State and Pernambuco State. It is strengthened the proposal of using different origins indicators on RSL vertical variation, georeferenced by high precision altitude GPS, adjusted by Brazilian Geodetic System benchmarks, maintained by the Brazilian Institute of Geography and Statistics - IBGE. All issues regarding the curve drawn by Castro et al. (2014) are answered based on field data, laboratory analytical techniques, radiocarbon dating as well as relevant literature.

RESUMO

The present paper aims to investigate the relative sea-level and the coastal evolution during the Holocene in the Rio de Janeiro coastline, based on geological and biological indicators. Using topographic survey, excavation and coring, and 14C dating of these coastal deposits and beachrocks outcrops, we have reconstructed a sea-level curve for the Holocene. For the first time on the Brazilian coast it was identified a negative record of relative sea-level during Late Pleistocene and Early Holocene transition. After the transition, a relatively rapid increase of sea-level began. At approximately at 8500 cal yr BP, the sea-level was 0.5 m below the current level, was overtaken for the first time in the Holocene, at approximately 7500 cal yr BP. The maximum level of +2.5 m was reached between 4770 and 4490 cal yr BP. At the point of maximum transgression, the sea-level began a general behavior of lowering until the present. These results confirm other data already obtained elsewhere along the Atlantic coast of South America. The results of this study are consistent with previous researches and they help to refine the Holocene sea-level record along the Brazilian coast.