Rocks Flashcards
How are igneous rocks formed?
When molten magma or lava cools and becomes solid
What is the difference between igneous rocks that have solidified on the surface or underground
On the surface - small crystals (e.g basalt)
Underground - large crystals (e.g granite)
How are sedimentary rocks formed?
When tiny particles settle on the ocean floor. Over time, more and more layers of sediment settle on top, The pressure causes the layers to harden (e.g chalk and limestone)
How are metamorphic rocks formed?
When sedimentary rocks comes under heat and pressure underground. Arrangement of crystals change (e.g marble)
What is an intrusive igneous rock?
It cools slowly under the ground because it is insulate by the surrounding rock. Forms rocks with large crystals
What is an extrusive igneous rock?
It cools quickly above the ground. Forms rocks with small crystals
How are crystals formed?
When atoms or molecules fitting together in rigid structures with regular lines and particle layers
How do fossils form in sedimentary rock?
- When organisms fall into the sediment,
- not enough oxygen to cause the organism to decay,
- organism has hard enough parts to leave a caste in the forming rock,
- water filtering through the rock deposits minerals in the caste
How can rocks be eroded?
By wind or water (into small fragments)
Why do different layers of rock erode at different rates?
The different layers have different properties (e.g solubility and hardness)
What chemical is in limestone, chalk and marble?
Calcium carbonate (CaCo3)
What are the problems with quarrying limestone?
- It creates noise and dust
- Destroys animal habitats
- Transportation contributes to traffic and road damage
What are the advantages of quarrying limestone?
- Provides jobs
- Industries are important for bother local and national economy
How is glass made?
By heating limestone, sodium carbonate and sand
How is cement made?
By heating limestone and clay
