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Haven of various species of Palearctic
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Climate
Generally, Borno and Yobe States experience dry arid climatic conditions, with mean annual temperature range of 280 C-290 C. However, the maximum temperature rises to over 480 C at the onset of the rains around May. The States have their coolest temperatures during December to February which is the Harmatan period with a mean temperature of 200 C-230 C. The area is characterized by two seasons, a long dry season and short rainy season. The mean annual rainfall in the Sahel is about 180mm/pa. It commence in July and ends October, whereas the dry season lasts for about 7-8 months (from November-June).
Topography
The conventional Chad Basin is an undulating drift-covered plain of irregular shaped sand dunes, depressions and sandy flats, which alternates with hummocky terrain. Broadly, the landscape in the North is of low relief with a succession of sand dunes and loamy clay or loamy peneplains. South of 110N latitude, upland of old sedimentary rocks of tertiary age towers over adjacent plains to a height of over 600m. These are the granitic Gwoza Hills in the south to southeasterly tip of Borno State and the Biu basalt Plateau of well-preserved volcanic cones in the south.
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