Waec Model Questions Vol1 2018 Geography Question 6

A field geologist examines a rock outcrop in the Jos Plateau and records the following observations: - The rock is coarse‑grained, composed mainly of quartz, feldspar and biotite. - It exhibits interlocking crystals with visible grain boundaries. - The rock has a hardness of 6–7 on the Mohs scale and a specific gravity of about 2.7. - No fossils are present, and the rock shows faint foliation that dips at 30° toward the southeast. Answer the following: a) Identify the most probable rock type (igneous, sedimentary or metamorphic) and justify your choice using the observed properties. b) Explain the geological processes that could have produced the identified rock, outlining the sequence from source material to the final rock. c) Discuss two engineering considerations that must be evaluated before using this rock as a foundation material for a new bridge in the area.