An assessment of Geomophic Processes Responsible for the formation of Tors in Seme, Kisumu County, Kenya.

Abstract

The formation of tors has been a major discussion in geomorphology for quite a number of years. According to the old Welsh language tors refers to a heap or pile of rock, tor a free standing residual mass of rock which rises abruptly from the, a surrounding smooth outcrop and gentle slopes of adjacent hills or even ridge crests (Ehlen,2004). Tors in the opinion (Romani, 2005) are conspicuous masses of rock that rise above surface normally common features of elevated granitic terrains. The main objective of this study was to assess the spatial distribution of tors and to determine the geomorphic process that explain the formation and the study was conducted in Seme sub-county, Kisumu County Kenya. Specifically, the study determined the relationship between geomorphic process that is Mass movement, Weathering and Water erosion in the formation of tors. The study employed non-probability method in getting the population size that has spatial and temporal representation of the area in the form of tor population within the administrative structures in East Seme. The target population was tors of height of 4metres and diameter of 7 metres, captured and spatially referenced, a total of 40 tors that also included geomorphosites such as the Kit-Mikayi, Luanda-Manya, Luanda-Boya, Kidi-Achiel and Kit-Maria were included in the sample. Primary data sets were used Tors sampled depending on different heights, rock samples, rock crevices, slope estimation and observation, the DEM, land use land cover data and weather data. Data Processing and Analysis involved measurement of tor height, diameter, lengths of cracks and crevices all in meters and tabulated in excel spread sheet and later analyzed to estimate the relationship between variables to be presented in graphical nature. The analysis methods used were both descriptive and inferential analysis techniques. The results mean of tor diameter 31.4146, mean of tor heights 18.8293 and mean of cracks lengths in tor 0.6129. The cracks were due to thermal variation, mass movement due to tectonic and water erosion is due to high peak of rainfalls in the area. The study established that leading geomorphic process in tor formation therefore are physical weathering, water erosion and to a lesser extent mass movement.