The aim of this paper is to characterize the geomorphology and analyze the terrain of the Bornu basin. This is critical to the understanding of the general landscape configuration, its evolution and morphodynamics in the basin. Mapping was carried using the Shuttle Radar Topographic Mission (SRTM) and Digital Elevation Model (DEM) data of the area. These set of data compliments the data generated from an extensive and detailed mapping of the area adopting the holistic approach geomorphologic field mapping technique. The basins slope generated from DEM of the area indicated five terrain categories. The western end of the basin has the highest slope of 755 to 1582m denoting the margins of the Biu and Jos plateau which slopes down to the lowest slope category of 256m at the shores of Lake Chad. These slope categories exhibits a variety of land forms ranging from rills, gullies, ponds, rivers, deltas, alluvial plains, ridges, hills and sand dunes of variable sizes, shapes and morphological characteristics. The Bama ridge which rises to height of 363m covering a distance of about 340 Km is a major land form in the basin. These land forms and others identified have been formed and are being fashioned by interplay of fluvial and Aeolian processes whose linkages are found to vary both in spatial and temporal dimensions.Detailed geomorphic and terrain analysis of the basin provides an exact and measurable picture of the relief form and land forms which are essential in the search for solid minerals, underground water, and oil and gas. In this 2 paper, the geomorphometric and terrain of the Nigerian section of the Chad basin (Bornu basin) was analyzed using information extracted and processed from the SRTM-DEM data, Landsat imagery, extensive field mapping and the review of previous literatures. The Study AreaNigerian section of the Chad Basin, known locally as the Bornu Basin forms the south western part of the Chad Basin in Nigeria and covers a landmass of about 2,335000Sq Km. It is one of Nigerian's inland basins occupying the northeastern part of the country and representing about one-tenth of the total area extent of the Chad Basin. The Basin is a large regional structural depression cutting across Cameroon, Central African Republic, Niger, Chad and Nigeria (Obaje, 2009). The Bornu Basin falls between latitudes 10 0 N and 15 0 N and longitudes 8 0 E and 14 0 E covering parts of Borno, Yobe and Jigawa States of Nigeria (Figure 1).

The characterization of lithofacies of the Yolde Formation at Briyel town in the Gongola Sub-basin of the Northern Benue Trough indicated coarsening upwards cycles composed transitional succession of six lithofacies that comprises of trough cross-beds, planar cross-beds, massive beds, ripple laminations, parallel laminations and mudstone. This coarsening and thickening upward symmetry is defined by a densely bioturbated mud dominated lower part transitionally grading into heterolithic interval composed thinly bedded sandstone and mudstones both of which developed below fair-weather wave base. This is capped by a succession of moderately bioturbated trough-planar crossbedded sandstone with poly-directional paleocurrent system. These assemblages reflect shoreface deposits and devoid of hummocky cross-stratification therein may account for a moderate wave oceanographic system. Evolution of this setting in the Gongola Sub-basin is indicative of a scenario of a broaden coastline in the coastal palaeogeography of the Yolde Formation typically suppressing due to frictional damping.

Facies evaluation carried out on the Yolde Formation at Gabukka locality in the Gongola Sub-basin of the Northern Benue Trough was aimed at enacting its paleo-depositional environment. The formation at this locality revealed an intercalated succession of massive bedded sandstone facies (Sm), planar crossbedded sandstone facies (Sp), ripple laminated sandstone facies (Sr), parallel laminated sandstone facies (Sl) and mudstone facies (Fm). These successions developed a thinning and thickening stratigraphic profile depicting periodic rhythmic signatures indicating deposits of tidal rhythmites. Thickening rhythmic packages are reflective of a spring tide whereas thinning phases are indicative of neap tide. These depositional sequences are genetic to intense tides conditions, thus an indexing a tide dominated oceanographic within the course of development of the Cretaceous Yolde Formation.

This research aims to evaluate the facies and facies association of the Yolde Formation at Kware stream in the Gongola Sub-basin of the Northern Benue Trough with objective of characterizing its paleodepositional environment. Six lithofacies consisting of trough crossbedded sandstone facies (St), massive bedded sandstone facies (Sm), planar crossbedded sandstone facies (Sp), ripple laminated sandstone facies (Sr), parallel sandstone facies (Sl) and mudstone facies (Fm) defining its stratal packages were skewed into distinctive assemblages of flaser, wavy and lenticular bedding. This present a fining upward signature with facies association typical of tidal flat system. This is evident of a coastal progradation with sequences reflecting migration of a supra-tidal mudflat over intertidal mixed-flat zone which progressively superposed subtidal sandflats. This is indicative of a coastal shoreline with a relatively progradational phase within the net transgressive regional framework of the Cretaceous Yolde Formation.

The facies analysis of the Cretaceous Yolde Formation at Gamajigo village in the Gongola Sub-basin of the Northern Benue Trough indicated fining upward a sequence characterized by the assemblages of five lithofacies that comprises of trough crossbeds, planar crossbeds, massive beds, ripple laminations, and mudstone. This fining upward architecture is defined by trough crossbedded sandstone with erosional contact at base overlain by interbedded sandstone and mudstones often displaying bi-direction paleocurrent patterns and growing mudstones content upwards moving into dominantly mudstones unit. This concurrently demonstrates dissipating energy intensity upwards as such reflecting a tide dominated system clearly of tidal channel depositional complex that most commonly develop in estuaries and tide dominated delta. Though on the account of the presences of Skolithos ichnofacies, a stressed hydrodynamic regime and indicating extension of tidal channel into the open sea may be very likely. This is generally indicative of a tide dominated oceanographic system in the advancing and inundating Cenomanian transgressive sea that define the coastal realm of the Gongola Sub-basin.