GEOLOGY AND THERMAL METAMORPHISM AROUND BELKA PAHAR AREA DISTRICT SIROHI (RAJASTHAN) ,

Abstract

Location The area is bounded by latitude 240 45' to 2450' and longitude 7?' to ?3l3'. The total area covered in the present study is roughly 12 Kma. The area lies in the Sirohi district of Rajasthan. The nearest railway station Is Sirohi road which is 800 Kms from Delhi as Delhi-Abmedabad line of the Western Railway. The area is connected to Sirohi road partly by metalled and partly by non-metalled road. The distance from area to Sirohi road is 30 Kms. Climate ,and Rainfall The climate of the area is generally warm. The summer starts in March and lasts in the end of June. Temperature goes up as high as 40-450 C in the months of May and June:. The average summer temperature is 3500. The monsoon starts in the early July and lasts for months and ends in mid October. The winter makes its appearance in early November and ends in late February. The rainfall averages between 100--lld cans. Drainage : There is no big river in the area. The only big drainage Syo~ta" is known as A1-&o Nallah which flows in the area almost through,major part of the s. ss4en. Some distance away from the area a river known as Jawai flows across which a dam has been constructed for irrigation purposes. The trend of the Nellah is roughly North South. Being a hilly region, numerous small n a11ha flow during monsoon and radial drainage pattern can be seen as it is a granite country which is a typical of hard rocks. Weathering : The chief agents of weathering in the region are wind, and rains. Wind causes abrasion and at the same time removal of the weathered products from the hill yldPen fir. Rain cause both Mechanical as well as chemical weathering. In chemical .weathering huge boulders are separated from the main r'' which are brought dorm by gravity action. Another type of Mechanical weathering observed.in the area is exfoliation in which curved plates of rock are stripped from a larger rock makes by the action of physical forces. 3 in the exfoliation process two types of weathered featured are seen in the area. Large, dome like hills., called exfoliation domes and rounded boulders usually referred as spheroidally weathered boulders. It seems that the forces that produce these two features originate in different forms. Due to chemical weathering the feldspars have been kaolinized. Quartz is quite resistant to chemical weathering and as a result it is found unaltered in the weathered granite. Soil and Vegetation The low lying area are generally underlain by alluvium and the soil type which is generally 4 t ed derived from granites is loamy type. Vegetation is very dense In the area and it is a part of the reserve forest. The crops are usually paddy and wheat. T opogra~hy and Qecm►orphology i Although the area is mostly covered up by alluvium even then it shows granite topography whereever it 2s exposed. Small hillocks exclusively of granite and undulating plains without any out crop can be seen I here. The granites showing peculiar weathering, characterised by fantastic piles of huge boulders giving rise to unstable positions can be seen in the nearby areas. The highest point i.s 1089 M above mean sea level knflx as Belka Pahar. The other high peaks in the area are 1016 meters and 880 meters above mean sea level. Geomorphologically the area can be divided Into three parts escapments, hill slopes, and plains. b4thel-19 Lithologic control on these features is quite obvious. G r granitesc form steep escapment and generally occupy the hill tops. Hill slopes are covered by the debris material derived from the weathering of granites. Plains are generally covered by the alluvium.........