This question was well attempted by the candidates. In question 4(a)(i & ii), most of the candidates could enumerate the economic importance of rocks to man and in agriculture.
In question 4(b), majority of the candidates could state the characteristics of igneous and metamorphic rocks.
However, in question 4(c), some of the candidates could not give a description of the
mode of formation of sedimentary rocks.
The expected answers include:
Description of the mode of formation of SedimentaryRocks
- derived from pre-existing rocks of all types/dissolved minerals/organic materials;
- the disintegrated materials are moved form site of origin and deposited elsewhere; by agents such as water, glacier, wind etc.
- the particles are deposited in layers/strata and cemented together by colloidal materials e.g. CaCO3, silica, iron oxides, mineral gellies etc;
