1.1 Study background
The earth surface is an essential part of the ecological system. Geographically land covers about 30% of the entire area of the earth surface and in it terrestrial animals and human beings live and dwell (Ogunji, 2014). Biologically, the land surface of the entire earth surface makes up a small proportion of the total body solid system of living things (UNICEF, 2011). The study area, Amuro-Afikpo and its environs is located in Ebonyi State, South Eastern Nigeria. The study area is accessible by Enugu- Abakiliki expressway and some track roads and footpaths. The area is located within the lower Benue trough. Geomorphologically, the area is composed of an alternation of high and low land with some of these low lands occupied by surface water bodies. The area is composed of sediments of the Upper Cretaceous and the Formation encountered is the Ezeaku, which has both shale and sandstone and the Aus-River group which is composed of shale and intercalation of sands. The igneous activity found in the area show a doleritic intrusion (silt) probably of the initial phase of the rift formation. The Amuro area offers a unique opportunity to study and understand the deformational processes and to determine the tectonic stresses active in the southern Benue Trough as the highly indurated nature of the sediments allow for an abundance of outcrops that is unmatched anywhere else in the region. The study area lies between longitudes 70171 E and 70511E, and latitudes 50 461 N and 60 31 N within the Afikpo syncline of the Cross River basin of the Benue trough.
1.2 Aims and Objectives of the Study
This project is aimed at detailed geologic studies to map and denote the lithologic units underlying the study area, make a detailed description of different rock types encountered in some outcropping units in Amuro and its environs near Amasiri, Ebonyi State, Nigeria. The scope covers:
1.3 Location and Extent
The area mapped is Amuro town and its environs, in Ebonyi state, Southeastern Nigeria and lies between latitude 5º 53 N 5º 58 N and longitude 7º 52 E 7º 56 E. It covers an area of about 60km2 (sixty square kilometers). Major access roads into the area are through the Abakaliki – Afikpo Road, Okigwe – Afikpo Road, and Okposi – Amasiri – Afikpo Road, as well as Cross River – Afikpo Road. Good network of roads link up such areas as Abaomege, Akpoha, Ibi, Amasiri, Amuro and Afikpo. The major towns in the area are Amuro, Amasiri and Ozara ukwu
1.4 Physiography of the area
Afikpo area is about 164 square kilometrrs in size with an undulating topography an elevation of 17m above mean sea level.
1.4.1 Topography
The study area consists of alternating sandstone ridges that strike in the NE-SW direction with intervening lowland formed by the shale units. The seasonal streams abound in the low land areas. The lowlands are sparsely vegetated. The set of sandstone ridge observed in the area have an estimated average elevation of about 200m above sea level, while the intervening low lying shale dominated plains are about 100m above sea level. Igneous intrusions were observed in the lowland areas.
1.4.2 Drainage
The mapped area is drained by the streams of the Cross River system and Ebonyi River (Asu River). The drainage in the area consist of series of which emerge from the ridge and cleaned to the plain valley which widen at the foot of the ridge. The lithology of the area affects the development pattern and density of streams. The drainage pattern is mainly dendritic with a few rectangular or trellis patterns and the streams haven’t reached matured stage. These drainages serve as source of water supply to some of the villages and communities. Springs and seepages abound in the study area contributes to the drainage of the area.
Fig 1.0 :Drainage of the study area.
1.4.3 Vegetation
The mapped area is sparsely vegetated. It is a mixture of eastern prototypes comprising of semi-savannah grassland with forest and swamps. It falls within the rain forest and savannah belts of the south-eastern Nigeria. The dominant vegetation is characterized by trees, shrubs, abundant palm trees particularly in the southern and central part of the area. Grasses are essentially found on the ridges and on the undulating shales too, while the trees tend to be more concentrated on the valleys (shales). The Prominent trees found in the area include Robinia pseudoacacia (the locust bean tree), and Elaeis guinensis (palm trees), which grow in clusters.
1.4.4 Climate
The study area has two distinct seasons, a wet season that lasts for eight months, and a dry season that lasts for four months. The period from April to November form the rainy season while the months December to March are dry. The months of December are cool and dusty because of harmattan while the period from February to March is the hottest. The annual rainfall varies between 1500mm and 2000mm, with the driest month recording less than 300mm of rainfall (Inyang, 1978). Relative humidity in the study area is generally high and ranges between 60% and 95% during the rainy season and fall below 60% during the dry season (Monanu, 1978; Nimako, 2008). The atmospheric temperature is intermediate from 27oC to 33oC with February and March as the hottest period/month in the area.
Fig 1: Drainage of the study area (Amuro)
Fig 2.: The picture shows the vegetation and topography of Amuro and its Environs. (Photograph taken behind Civic Center, in Amuro Afikpo)