From Rock To Soil Flashcards
What are rocks?
Hard materials made of natural compounds that make up most of the earth’s surface and earth below the surface.
Natural compounds
Mixture of minerals
Minerals’ existence in rock
Crystal form
What is quartz?
Silicon dioxide
What are feldspars?
A group of aluminosilicate minerals that contain Calcium, Potassium and Sodium.
Uses of rocks
Construction purposes, obtaining metals from ores or gemstones from minerals.
Types of rock
Igneous, metamorphic and sedimentary
Weathering
Rock broken down by the action of things in its environment.
How does the rock cycle help us?
Building materials (limestone, marble, granite), gemstones, uplift gives access to materials, creates soil.
Freeze thaw weathering
Freezing and thawing expands cracks in rocks and breaks them up.
Reduction in pressure
Causes rock to expand and layers to peel off like an onion, exfoliation.
Heating and cooling
Causes expansion and contraction of rock, causes cracks and breaks.
What is Biological weathering?
Plants and animals cause rocks to break up by growing in them/ hitting them.
What is chemical weathering?
Rain is slightly acidic, as it reacts with the carbon dioxide in the air, this then dissolves the calcium carbonate in limestone and dissolves it.
How is clay formed?
Water + Feldspars = Clay
How is quartz created?
Quartz is impermeable, so when a rock containing quartz breaks down, the quartz crystals are set free as sand.
How is soil created?
Sand + Clay + Rotting Vegetation = Soil
What are intrusive igneous rocks and how are they formed?
- Intrusive igneous rocks are igneous rocks that are formed inside the earth’s crust.
- They are formed when magma underground moves higher up due to the pressure and its minerals begins to crystallise at different temperatures, the crystals then lock together, forming rocks such as granite.
- These rocks tend to have bigger crystals.
What are extrusive igneous rocks and how are they formed?
- An extrusive igneous rock is any rock derived from magma that was shot out from Earth’s crust.
- They are formed when magma shoots out of a volcano as lava and cools immediately, causing rocks such as basalt to form.
- These tend to have smaller crystals.
What dives the rock cycle?
Tectonic plates.
What are the different layers of the solid profile?
Humus, topsoil, subsoil, rock that is being weathered, bedrock.
What does the humus do?
It is a thin layer of rotting vegetation, the nutrients in it return back to the soil.
What does the topsoil do?
The topsoil is rich in humus and minerals from rock, so it’s good for growing crops.
It contains sand that makes it crumbly and helps the roots to spread better.
What does the subsoil do?
The subsoil has only a little humus, but a lot of minerals, tree roots reach here.
