Rocks and Minerals - 8.1 Igneous Rocks [ARCHIVE] Flashcards
What is the crust?
The outermost solid layer of the Earth.
What is the mantle?
The layer under the crust, which is much hotter and made of different chemicals.
What do the upper part of the mantle and the crust have in common?
They are both rigid solids, therefore, having similar physical properties.
What are the crust and the upper mantle together known as?
The lithosphere.
What is the name of the ‘plastic’ layer beneath the lithosphere?
The asthenosphere
Why is asthenosphere called the ‘plastic’ layer?
The rock of the mantle flows very slowly, similar to plastic that has been heated.
What is the core of the Earth?
A very dense layer of the Earth that is composed of mostly iron and nickel.
What is the difference between the inner and outer core?
The inner core is solid, but the outer core is liquid and can flow.
What are crystals?
Solids that are formed when particles in liquid rock clump together as magma cools and solidifies.
What is the difference between small and large crystals when they’re formed?
Small crystals - Magma cools quickly because it doesn’t give crystals a long time to grow.
Large crystals - While the magma is liquid, particles can move around and add to nearby growing crystals, making it larger.
What are minerals?
Chemical substances in a rock with particular combinations of atoms.
(can be identified by their physical properties.)
What are the characteristics of igneous rocks?
-Hard
-Strong
-Made of interlocking crystals
How do geologists classify if an igneous rock is intrusive or extrusive?
By looking at the…
-texture (smooth, grainy, lumpy, has interlocking crystals)
-colour (dark/light depending on the minerals the rock contains).
What do extrusive rocks have in them?
Rapid cooling causes minerals to solidify quickly in rocks, preventing large crystal growth and forming VERY SMALL CRYSTALS.
Why do many extrusive rocks have holes or spaces in them?
Because of gas bubble trapped when the magma cools quickly.
