Earth and Universe Flashcards
What is the crust?
The outer layer of Earth and the thinnest. Between 8km and 40km thick. Thinner under the oceans that on land. Contains rocks and minerals.
What is the mantle?
The thickest layer of Earth. Made from solid rock that can flow - plastic rock. It moves in big circles caused by convection currents. It is where the hot rock rises and cold rock sinks.
What is the inner core and outer core?
Made of mainly iron and nickel. Outer core is liquid and inner core is hotter but the metals are solid. The outer core is where the magnetic field comes from - this makes compasses work.
What is the order of the layers of the earth starting from the outside layer?
Crust, mantle, outer core, inner core.
What is cementation?
When minerals of the rock crystalise to
What is compaction?
When sediment is compressed.
What is deposition?
Sedimentary being carried.
Why do sedimentary rocks have layers?
They have layers as a result of different types of sediment settling at different times. Epsom salt is made from the dissolved minerals of magnesium and sulfur. This is the ‘glue’ that holds it together.
How are metamorphic rocks formed?
Earth movements can cause rocks to be deeply buried or squeezed together. As a result, the rocks are heated and put under great pressure. The rocks do not melt, but the minerals they contain are changed chemically, forming metamorphic rocks.
What are the properties of metamorphic rocks?
- Formed when either igneous or sedimentary rocks are changed.
- Heat and pressure cause the elements in the original rock to react and re-form.
- They are crystalline and often have a “squashed” (foliated or banded) texture.
- Metamorphic rocks are usually highly resistant to weathering, making them very hard-wearing.
What are some examples of igneous rocks?
Granite, obsidian, basalt, gabbro.
What are the properties of igneous rocks?
- Hard.
- No fossils.
- Crystals.
-No layers.
What is a fossil?
The preserved remains or traces of a dead organism. The process of its formation is called fossilisation. Fossils only form under special conditions as most bodies just rot away.
What is physical (freeze-thaw) weathering?
When water seeps into a gap in the rock and freezes when the temperature drops. Water expands and puts pressure on the rock and ice melts the next day. This causes the gap to largern and this repeats until the rock breaks.
What is physical (onion skin) weathering?
When it is hot during the day and cold during the night. This causes the surface of rock to expand and contract frequently until it eventually breaks off.
What is chemical weathering?
Rainwater is slightly acidic (carbon dioxide dissolved in it to give carbonic acid). It can react with limestone, chalk or marble as they are made from calcium carbonate. Sulphur dioxide gas makes rainwater more acidic - this acid rain weathers the rock much faster.
What is biological weathering?
Plant roots can penetrate into even the toughest rocks over time. This can cause the rock to break apart. Animals walking on the rocks can also weather them.
What happens during a solar eclipse?
The moon blocks the sun’s rays from reaching part of the Earth.
What objects in the universe reflect their light from stars?
Moons, planets, satelights, comets.
What happens during a lunar eclipse?
The Earth blocks the sun’s light from reaching the moon.
What percentage of the following gases are in the atmosphere?:
- Nitrogen.
- Oxygen.
- Carbon dioxide.
- Argon.
- Nitrogen = 79%.
- Oxygen = 21%.
- Carbon dioxide = 0.004%
- Argon = 1%.
What are the 5 parts of the carbon cycle?
- Photosynthesis (involving all plants).
- Respiration (involving all animals and plants).
- Combustion (burning of fuels).
- Decomposition.
- Comsumerism (carbon being passed along a food chain).
What are the properties of sedimentary rocks?
