Define the term atmosphere. (b) State the composition of the inner core. (a) Name three types of folds. (b) State three factors that determine the folding of crustal rocks.

1(a) Definition of the term atmosphere

The atmosphere is a thin layer of gases surrounding the Earth held by the Earth's gravitational pull.

1(b) Composition of the inner core

The inner core is composed primarily of solid iron (Fe) and nickel (Ni).

2. Three types of folds

• Simple folds
• Monocline folds
• Overthrust folds

3. Three factors that determine the folding of crustal rocks

1. Intensity of compressional forces: Greater force leads to tighter folds.
2. Temperature: Higher temperatures increase rock ductility, allowing folding without breaking.
3. Rock type and thickness: Plastic, thicker layers fold more easily than brittle, thin ones.