Geography 2006 Jamb Examination

Nigeria experiences two dominant air masses: the tropical maritime air mass from the Atlantic and the tropical continental air mass from the Sahara.
Their seasonal dominance creates a clear alternation in weather — moist winds from the ocean bring rainfall, while dry continental winds cause dry periods.
This interaction produces the well-known alternating wet and dry seasons.

Port Harcourt hosts Nigeria's first petroleum refinery, established due to its proximity to crude oil fields and coastal location.
This made transportation, processing and export of refined products efficient.
Other listed locations host later refineries, not the first.

Conglomerate is formed from the compaction and cementation of physically weathered rock fragments, making it a mechanically formed sedimentary rock.
Chalk and dolomite are chemically or organically formed, while coal is organic.
This makes conglomerate the correct example of mechanical formation.

Altitude strongly determines temperature because temperature decreases with height at an average lapse rate of about 6.5°C per kilometre.
Higher places are therefore cooler regardless of latitude.
Other factors influence climate but do not control mean temperature as fundamentally as altitude.

Historical antecedents, such as early settlement zones, trade routes and colonial influence, shape enduring population clusters.
Regional migration further redistributes people based on economic opportunities and social factors.
This combination best explains present population patterns in West Africa.

Cold ocean currents along the Horn of Africa suppress evaporation and limit moisture availability, leading to arid conditions.
This results in low rainfall, creating large dry zones.
Warm currents or cyclone belts have little effect compared to the strong influence of cold currents.

Colonial railway systems in West Africa were built primarily to transport raw materials such as cocoa, timber and minerals from the interior to coastal ports for export.
This economic motivation shaped the layout and direction of the rail lines.
Other functions were secondary or incidental.

Francophone countries are nations in Africa where French is an official language due to historical French colonisation.
Benin Republic, Algeria, Côte d'Ivoire and Chad all use French officially.
The other options include countries that are not predominantly French-speaking.

Warri developed as a major port in the Lower Niger region due to its strategic waterways and proximity to resource-rich hinterlands.
It handled significant export and import activities historically.
Other towns listed did not dominate trade to the same extent.

A high hill blocks direct lines of sight between two locations, reducing inter-visibility.
Features like valleys or rivers may separate settlements but do not obstruct visibility as effectively as elevated terrain.
Thus, high relief features most strongly limit sightlines.