Apart from metamorphic rocks, name two other categories of rocks.

KCSE Geography Paper 1 2017 Section B Question 7.

(a) (i) Apart from metamorphic rocks, name two other categories of rocks.

• Sedimentary rocks
•  Igneous rocks

(ii) Describe the following processes of formation of metamorphic rocks.
. Dynamic metamorphism 
. Thermal metamorphism 

 Dynamic metamorphism

•  Original rock is subjected to intense pressure.
•  Pressure is caused by compressional force when the crustal plates collide.
•  The great pressure alters the mineral line up in the rock] structure.
•  The rock changes their physical appearance and characteristics forming a new rock.

 Thermal metamorphism

•  Rocks are subjected to intense heat.
•  Heat may be due to rocks being buried at great depths/due to contact with magma.
• The hot magma melts the minerals of the original rock, they cool and solidify to form a totally different rock/recrystallize the rock grains.
•  New minerals may also be added into the rock by the intruding magma.
•  The new rocks change their physical appearance/chemical composition.

​(b) Explain three ways in which rocks are significant to human activities in Kenya.

•  Rocks contribute to formation of different soils that are used for agricultural activities.
•  Some rocks contain valuable minerals/substances that can be used in industries/ for fuel.
• Some rocks provide building/construction materials.
• Some rock outcrops attract tourists such as granitic tors in Kakamega/Kisumu.
•  Some rocks are used for carvings such as the Kisii soapstones.
•  Some rocks provide raw materials for industries example limestone.
•  Some rocks act as underground water reservoirs to provide water for irrigation / domestic use.
•  Some rocks are used for educational purposes/research.
•  Provide salt licks as a source of minerals for livestock people.

(c) You intend to carry out a field study on the types of rocks within the school locality.

(i) Identify three items that you will carry during the study.

•  Hammer
•  Polythene bag/carrier bag
•  Notebook/stationery
• Route map
•  Jembe
•  Geological map

(ii) State three activities that you will be involved in during the study. 

• Taking notes
•  Observing the rocks
• Collecting samples
•  Asking/answering questions/interviewing
•  Drawing sketches
•  Measuring
•  Taking photographs
•  Labelling samples
•  Digging out! breaking rocks.

​(iii) List three types of metamorphic rocks that you are likely to identify.

• Slate/schists
•  Quartzite
• Graphite
•  Gneiss
•  Marble
•  Hornblende

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