A influência da ação antrópica na classificação dos materiais inconsolidados da cidade de Ouro Preto - MG

Abstract

Many authors consider anthropogenic activity one of the most active modifying agents on the physical environment. Its intrinsic relationship with other environmental factors such as water, unconsolidated materials, rocky substrata, ground relief and others should be more intensely studied. In the current research the procedures and results in the classification of unconsolidated materials in the Brazilian town of Ouro Preto are provided. Materials were analyzed according to their genesis and evolution, relative thickness, position in relief and lateral distribution. Field and lab assays were undertaken in specific sites of samples. The latter were determined by geomorphologic criteria so that homogeneous units throughout the area could be obtained. With regard to their genesis and evolution the unconsolidated materials were first classified into residual (saprolite and developed) and reworked material (colluvial, talus and alluvial). However, a new class was required and has since been included in the analysis. It comprised materials associated with anthropogenic (technogenic) activities hailing from mining refuse, non-compacted earthwork and debris deposits. due to their texture and structure these materials could not fit in the residual and re-worked classification. Features produced by anthropogenic activities were classified according to their density (number of features) in sand extension (m2) and significant quantify of these forms. A new type of class of materials was thus required. Eighteen units, divided into basic and composed, were selected. Criterion of separation was due to isolated and sets of occurrences of materials related to differences in origin and type of human activity. Results showed the importance anthropogenic activities have on physical environment. In the future the anthropogenic or technogenic factor should be taken into account in all analyses.