A Cidade do Rio de Janeiro : evolução física e humana

Resumo

The present article is a study of the region where ls located the city or Rio de Janeiro, capital of Guanabara's State.

            It is a trial do analyze that principals physicists aspects and about the modifications printed by man in the landscape in those 400. 0 years of occupation.

            Placed in the occidental margin of Guanabara's Bay at 23°S. and 43°Gr., the city has a tropical humid climate responsible by that exuberant vegetation that covers its elevations.

            The actual morphology, that is characterized by mountains, isolated mounds and islands crystallines and metamorphics, and by Quaternary flats, results by a series of factors.

            A intense regional tectonism in the Pre-Cambrian is responsible by the fold of rocky mass which departed to be shaped by the erosion.

            The erosive action was interrupted in the Jurassic, when it happen volcanic eruptions and nephelinic sprends, and at the cenozoic, when diastrophic movements they originated a series of imperfections and a basculement to the north of Serra do Mar and of these coastal massives. Thus it was created a depression at the angle of flaw where is placed the Guanabara's Bay.

            Some hills, which are situated in several areas of Guanabara, resemble like been created by climatic oscillations of Pleístoceno also by alternates periods of erosion and accumulation. at last by the variations of the sea level.

            That same climatic oscillations had flowed in forms like "sugar loaf" of several hills pertaining to State of Guanabara.

            The quaternary plains they result of the accumulation of alluvial sediments and maritime the presence oi beach's sand and shells in the interior of the urban nucleus just tell u1o presence of the sea in the past on this areas.

            Equally are examined the principals geomorphic process responsible by the shaped of the elevations, like a differential erosion a fluvial erosion and the movement of detritus by the slopes.

            That process. aggravated by a high temperature and humidity are hasan by the tytropic erosion perceived across the havoc and by the cultivation systems applied in Guanabara since the colonial period.

            When the Europeans become established in the hill of Castelo, around this mound and around the nearly elevations either, that low-lands its been vast swamps.

            The man had a necessity to descend downhill and to extend himself to head for the swampy plain. And the demand to new spaces had led himself to heap with not many equipments the areas what be needed in those days.

            According to the increase of the city becoming a great port commercial, financier and administrative center, but man needed more space.

            The city grew lineally between the saw and the sea.

            To transpose that topographic's obstacles, man had started to tear down the mound of a central area with the dismounting material he continued the embankment that are done with new technical and financier resources. Even the border of the bay it is been modified.

            The connection between those several quarters has been improved with the opening of tunnels in the granite-gneissic mounds, and also with the opening of transverses roads to the actual lengthways roads.

            Today the city of Rio de Janeiro is one of the most important cities of the country. In spite of Brasilia which have now the title of federal capital, Rio de Janeiro continues to represent extraordinary influence in those economic, financier and cultural sectors in Brazil.