Fundamentos e reconstrução de antigos níveis marinhos do quaternário

Abstract

The Quaternary Period has a very short duration in the Earth's history, but it is the most important because it represents the time interval in which we live. It is one of the most studied and known chapters or, perhaps, just for this, many are the doubts about the evolutionary history of the Earth during this period. Multiple aspects related to the "reconstruction of the ancient sea levels during the Quaternary" are here focused. The relative sea level fluctuations are produced by true variations of the sea level (eustasy) and by changes in the land level (tectonism and isostasy). So, sea level in a certain point of the coast is represented by an "instantaneous" resultant of complex interactions between the surfaces of ocean and continent. The changes of the relative sea levels are reconstructed through several evidence of these fluctuations, which must be recognized in time and space. To define their situation in space is necessary to know their present altitude in relation to their original altitude, that is, to determine their position in relation to the sea level during their formation or sedimentation. Their situation in time is determined by measuring the moment of their formation or sedimentation, using for this the dating methods (isotopic, archeological , etc.). When numerous ancient sea levels could be reconstructed, spreaded through a considerable time interval, is possible to delineate the sea level fluctuation curve for this period.