The Rock Cycle and Soil Formation

Which process forms igneous rock?

• Heat and pressure

• Cooling and solidification

• Weathering and erosion

• Compaction and cementation

Answer explanation

Igneous rock forms through the process of cooling and solidification of molten material (magma or lava). This distinguishes it from other rock types formed by different processes like compaction or weathering.

What type of rock is formed from layers of sediment?

• Igneous

• Sedimentary

• Metamorphic

• Magma

Answer explanation

Sedimentary rocks are formed from the accumulation and compaction of layers of sediment. This process distinguishes them from igneous rocks, which form from cooled magma, and metamorphic rocks, which arise from existing rocks under heat and pressure.

What is the process where sediment is compacted and cemented into rock?

• Weathering

• Erosion

• Lithification

• Melting

Answer explanation

The process where sediment is compacted and cemented into rock is called lithification. This involves the transformation of loose sediments into solid rock through pressure and chemical processes.

Which rock type can be changed into another rock type through heat and pressure?

• Igneous

• Sedimentary

• Metamorphic

• All of the above

Answer explanation

Metamorphic rocks are formed from existing rocks (igneous or sedimentary) that undergo changes due to heat and pressure. This process transforms them into a different rock type, making 'Metamorphic' the correct answer.

What is the driving force behind the rock cycle?

• Wind

• Water

• Plate tectonics

• Gravity

Answer explanation

The driving force behind the rock cycle is plate tectonics, which involves the movement of Earth's lithospheric plates. This movement causes processes like volcanic activity and mountain building, driving the transformation of rocks.

What is the main component of soil?

• Sand

• Humus

• Minerals

• All of the above

Answer explanation

Soil is composed of various components, including sand, humus, and minerals. Each plays a vital role in soil health and fertility, making 'All of the above' the correct answer.

Which factor does NOT affect soil formation?

• Parent material

• Climate

• Moon phases

• Organisms

Answer explanation

Moon phases do not influence soil formation, while factors like parent material, climate, and organisms play significant roles in the development of soil. Therefore, moon phases is the correct choice.

The uppermost soil horizon, rich in organic material, is called:

• A-horizon

• B-horizon

• C-horizon

• Bedrock

Answer explanation

The A-horizon, also known as the topsoil, is the uppermost layer of soil rich in organic material, making it crucial for plant growth. The B-horizon and C-horizon are deeper layers, while bedrock is the solid rock beneath the soil.

What is humus?

• Small rock fragments

• Decayed organic material

• The process of soil formation

• A type of mineral

Answer explanation

Humus is decayed organic material that enriches soil, providing essential nutrients for plants. It is distinct from small rock fragments, the process of soil formation, and minerals, making it the correct choice.

Which type of soil is best for plant growth?

• Sand

• Clay

• Loam

• Silt

Answer explanation

Loam is the best soil for plant growth because it has a balanced mixture of sand, silt, and clay, providing good drainage, nutrient retention, and aeration, which are essential for healthy root development.