Celia Regina de Gouveia Souza

Relação solo-relevo-substrato geológico nas restingas da planície costeira do estado de São Paulo

Atributos morfologicos de 28 pedons, descritos e amostrados em cronossequencias, e datacoes absolutas por luminescencia (TL e LOE) e 14C foram utilizados para elucidar os principais fatores envolvidos na formacao e evolucao dos Espodossolos nos depositos marinhos quaternarios da planicie costeira do Estado de Sao Paulo. Os solos estudados localizam-se nos municipios de Bertioga (Baixada Santista), Cananeia e Ilha Comprida (Litoral Sul). Essa abordagem, pouco comum nos estudos dos ambientes de planicie costeira brasileiros, possibilitou as seguintes interpretacoes: (a) o relevo, a dinâmica hidrica e o tempo (incluindo as variacoes do nivel relativo do mar) sao os principais condicionantes da diferenciacao espacial dos Espodossolos nos terracos marinhos; (b) os Espodossolos mais antigos e bem drenados, devido as condicoes de relevo e rebaixamento do nivel do lencol freatico, apresentam grande variabilidade e diversidade de seus horizontes e atributos morfologicos, diferindo daqueles mal drenados (antigos ou jovens), em que os horizontes sao mais homogeneos; (c) os Espodossolos mais antigos, quando bem drenados, mostram-se em avancado estadio de degradacao, enquanto os mal drenados encontram-se bem preservados, indicando que a sua genese e permanencia na paisagem estao ligadas ao relevo, que, por sua vez, controla a dinâmica hidrica; (d) os Espodossolos mais evoluidos e antigos, dotados de horizontes cimentados (orstein), podem ser considerados indicadores pedolitoestratigraficos dos depositos marinhos pleistocenicos da Formacao Cananeia; e (e) a genese do horizonte orstein se deu em condicoes topograficas e hidrologicas preteritas diferentes das atuais, indicando se tratar de solos poligeneticos ou paleossolos.

PRAIAS ARENOSAS OCEÂNICAS DO ESTADO DE SÃO PAULO (BRASIL): SÍNTESE DOS CONHECIMENTOS SOBRE MORFODINÂMICA, SEDIMENTOLOGIA, TRANSPORTE COSTEIRO E EROSÃO COSTEIRA

This paper presents an overview about the state-of-art of studies on oceanic sandy beaches from the State of Sao Paulo, within the Coastal Geomorphology point of view. These studies embrace a sort of thematic issues, in special: beach profile monitoring, textural (grain size) parameters, heavy minerals assemblage and related indices, beach sedimentary dynamics, beach sedimentary budget, sediment transport patterns (morpho-textural and wave modeling methods), long term shoreline changes (remote sensing analyses), morphodynamic classification, coastal erosion and associated risk, and environmental sensitivity for oil spill. Some results related to morphodynamic classification, grain size parameters behavior, longshore drift patterns, and coastal erosion (indicators, causes and risk assessment) are showed for the seven morphodynamic sectors that this coast is comprised.

The Bertioga Coastal Plain: An Example of Morphotectonic Evolution

The Bertioga coastal plain, located in the metropolitan region of Baixada Santista (central coast of Sao Paulo state), contains nearly all of the types of depositional systems that are found on the rest of the Brazilian coast, in spite of its highly restricted area that is less than 6 km wide. Similar to other coastal plains, Bertioga’s evolution was associated with variations in climate and the relative sea level (SL) during the Quaternary period. However, the evolution was also influenced by tectonic pulses that produced the following features: (a) a seismic signature indicating a normal fault in the central part of the coastal plain, which depressed block faces the Serra do Mar mountain range, suggesting the presence of a hemigraben (“Bertioga Graben”); (b) a sedimentary column thicker than 100 m in the central part of the coastal plain; (c) the presence of morphotectonic features on the coastal plain (anomalous arrangement and spatial distribution of some Quaternary units (QUs), drainage anomalies, and sets of systemic fractures in marine terraces) and on the Serra do Mar (fluvial capture of the Guaratuba River and triangular facets); (d) the preservation of marine terraces and fluvial deposits that are older than the Cananeia Formation (Marine Isotope Stage—MIS 5e, 100–140 ka); (e) differential control of Holocene marine and alluvial sediments throughout the coastal plain; and (f) the presence of guide layers in Pleistocene and Holocene deposits with throws up to 7.5 m. Thus, the evolutionary model of this coastal plain can in some ways be compared with those proposed for most Brazilian coastal plains, but with the peculiarity that it shows rare features of the transgressive–regressive event that is correlated with MIS 7 (240–260 ka) and has been affected by at least two tectonic pulses at the end of the Pleistocene and one pulse during the Middle to Upper Holocene. The recent creation of the Restinga of Bertioga State Park, embracing nearly half of the coastal plain, will enable the conservation of much of the rich plain’s biodiversity and protect its important geological–geomorphological heritage, strengthening proposals for future geosites for geoconservation according to the principles set forth by UNESCO.