PHYSICAL SETTING

Posted by on 2/10/2003 12:07:51 PM
Post Comment PHYSICAL SETTING Nigeria

Geology and Relief: Sokoto State is located within the Illumeden basin, which is surrounded to the east and south by the

Sokoto Cement Industry Complex
Sokoto Cement Industry Complex

precambrian basement complex. Within the State, there is no outcrop of basement complex. Rather, it is covered by a series of sedimentary rocks, which have been deposited over the basement complex. These sediments were laid down under varied environmental situations ranging from continental to marine events. The sedimentary rocks in Sokoto State have been classified under four major categories.

The first category is the Gundumi formation, which is the oldest sedi mentary rock in the state directly overlying the basement complex. It is made up of sandstones and clays, all of continental origin. The sandstone portion of the formation contains a lot of water and is currently being harnessed through boreholes. The second category is the Rima group of three distinct marine sediments, namely, the Taloka, Dukamaje and Wumo formations.

The Taloka, which is the oldest formation in the Rima group, consists of multiple layers of sandstones and shales. The sandstones in this formation contain a lot of water. The Dukamaje formation is shaly and nonaquiferous. The Wumo formation consists of one layer of sandstone. The third category of sedimentary rocks in Sokoto State is referred to as the Sokoto group which is of marine origin. It consists of two main formations the Dange and Kalambaina formations.

The Dange formation consists of clays and shales, while the Kalambaina for mation, which overlies the former, is made up of limestones. This group is also aquiferous. The fourth category of sedimentary rocks in the State is the Gwandu formation which occurs in the north western and southern parts of the state. This formation consists of clays and sandstones with a high potential for groundwater.

Usmanu Danfodyo University Teaching Hospital, Sokoto
Usmanu Danfodyo University Teaching Hospital, Sokoto

The basement complex on top of which the sedimentary rocks are overlain occurs in Sokoto State to a depth of 500m. It consists of the oldest granites, gneisses, migmatites, schists and other metavolcanics which are crystalline and imperme able. The relief of Sokoto State is generally a low land with an average height of 300m above sea level referred to as the Sokoto plains.

Davis (1982) characterised Sokoto's relief as a monotony of low land interrupted by isolated flattopped hills (mesas) and escarpments. The escarpments are found in Dange and Kalambaina and, along with the hills, they rise up to 488m. Minerals such as clay, gold, kaolin, gypsum, marble, lignite, feldspar and lime stone can be found in the state.

Drainage: Sokoto State is drained by the Rima River and its tributaries, most of which rise in the southeastern part of the state and in the neigh bouring Kaduna State. While the Bunsuru and Gangere Rivers flow in a northerly direction, joining the Rima near Sabon Birni, the Sokoto, Zarnfara and Ka tributaries, on the other hand, flow west wards to join the Rima. In their upper reaches, all the tributaries flow over basement complex rocks. Their valleys are rather narrow and restricted until the rivers enter the area of young sedimentary rocks, where they flow through broad valleys.

Climate: The climate of Sokoto State is tropical continental and is dominated by two opposing air massestropical maritime and

State House of Assembly Complex, Sokoto
State House of Assembly Complex, Sokoto

tropical continental. The tropical maritime is moist and blows from the Atlantic, while the tropical continental air mass, which is dry, blows from the Sahara Desert.

The rainy season while the tropical continental air mass predominates during the dry season. Much of the rain in Sokoto State falls between June and . September in the north and from April to October in other parts. The annual rainfall is between 500mm in the north and 1300mm to the south.

Moreover, the state is characterised by two extreme temperatures relative to its tropical position viz. the hot and cold seasons. The highest temperature during the a hot season is experienced in the months of March/April. Between November and February, there is the prevalence of harmattan, characterised by very cold temperatures and dustladen winds and often accompanied by thick fog of alarming intensity.

Vegetation: The whole state falls within the Sudan Savannah. The vegetation is characterised by thorny species with a scatter of acacia specie. The river courses are lined with dum palms, which are interspersed with a herbaceous cover of annual grasses.

Soils: Sandy topsoil with clayey subsoil are common, except along the flood plains of the river valleys where alluvial soils predominate. To the north of the state, especially along the border with Niger Republic, the undulating plains are covered by aeolian deposits of variable depth. These support light sandy soils. However, due to its geographical location, the state suffers from the scourge of desertification and occasional drought.




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