Neco Model Questions Vol1 2017 Geography Question 6

Three rock samples have been collected from different locations in the Jos Plateau region. Their main characteristics are described below. Sample A: Coarse‑grained pink rock, visible crystals of quartz, feldspar and mica; texture is phaneritic. Sample B: Fine‑grained gray rock, composed mainly of sand‑sized quartz grains cemented by silica; ripple marks are present on its surface. Sample C: Foliated metamorphic rock with alternating bands of mica and quartz; texture is schistose. Answer the following: a) Classify each sample as igneous, sedimentary or metamorphic and give a brief justification. b) The geological history of the area involved three major events: (i) deposition of sediments that later formed Sample B, (ii) burial and metamorphism that produced Sample C, and (iii) intrusion of a granitic magma that solidified as Sample A. Describe the sequence of these events and explain the processes that link the three rocks. c) Identify two economic uses of each rock type in Nigeria and briefly explain why the rock’s properties make it suitable for those uses.