Os processos erosivos e suas implicações na evolução da paisagem atual da Serra do Tepequém - RR

Abstract

The Tepequém saw area that is the object of study is located at the northern end of the Roraima state in the county of Amajarí. The top of the mountain ridge has a differentiated morphology, with varying altitudes reaching 1100m. This region was the scene of several geological, geomorphological and historical studies, which record important events in its history of evolution of the landscape, such as diamond mining activity. This study aimed to understand the erosive processes and their influences on the patterned of the current landscape of Tepequém saw. To understand the theme was conducted bibliographic and cartographic survey of previous studies as well as acquisition of field data as morphometric measurements on the depth, width and length of linear erosional features; identification and measures of micro erosional features; soil profile description in gullies wall and soil sampling at different horizons. Later, analyzes were performed granulometric, pH, porosity, density and mineralogical of the soils. The current modeled of the Tepequém saw is subject to the geologic structures of faults and fractures that affect the landforms and drainage present at the top, beyond the shallow soils and incoesos partially covered by vegetation. These features combined with high levels of rainfall contribute significantly to erosion and result in the formation of ravines and gullies in the areas of plains and slopes of hills and mountains. Were identified micro erosive features in the surrounding wall and thalweg of erosive chutes, these features undermine the places where they settle and assist in the advancement and growth of erosions. Overall, the gullies develop in areas of plains, and fewer on the slopes of hills and hills. The morphologies were identified: linear, forked and mixed. The soils are predominantly sandy, represented by fine to medium sand, of angular morphology subangular. The density of the soil varied for each horizon, as well as the porosity and pH. The highest concentrations of organic matter were identified on the horizon A. The mineralogical composition showed higher concentration of quartz. The staking of the gully pointed further evolution in the portion amount on the right wall, while the evolution of the gully Hill was much lower. Therefore, the Serra do Tepequém has been sculpted by erosion processes that promote the evolution of the present landscape.