Unit 2 Topic 2: The Earth’s Crust
Key Vocabulary:
1. Continental Crust: crust under the continents.
2. Ocean Crust: crust under the oceans.
3. Tectonic plates: huge pieces of Earth’s crust and upper mantle
A. Continental Crust:
1) Made up of different rocks like granite & basalt (types of igneous rocks)
2) Granite is light colored and made mostly of silica.
3) Basalt rock is dark-colored and made mostly of iron & magnesium.
4) Basalt is denser than granite because iron is dense.
5) Continental crust is old.
6) Continental crust was once molten (hot fluid) that cooled and formed solid rock.
B. Ocean Crust:
1) Made mostly of basalt and is very dense.
2) Ocean crust is denser than continental crust.
3) Ocean crust is younger than continental crust.
4) Ocean crust is always becoming new crust.
5) Two ways that new crust forms: old crust sinks down inside the Earth & melts OR
melted material rises up, cools, & becomes new crust.
C. Tectonic Plates:
1) There are 12 major plates and many smaller plates.
2) Continents & oceans sit on top of tectonic plates.
3) Plates move due to forces inside the Earth.
4) Plates can collide (bump into each other).
5) Plates can slide past each other.
6) Plates can spread apart (crack forms). Molten material rises in the crack and mountain
chains called mid-ocean ridges form
Homework Comparatives: Harder and more awful are the comparatives of the adjectives hard
and awful. Most adjectives of one syllable form the comparative by taking the –er ending.
Many adjectives of two or more syllables form the comparative by combining with the word
more. Example: a hard rock--a harder rock
an awful man--a more awful man
Directions: Write the one or two words that will form the comparative of each of the following
underlined adjectives.
1. Slow: Tectonic plates move ______ than turtles.
2. Hot: Earth’s mantle is _____than the crust.
3. Common: Basalt is _____ in ocean crust.
4. Frequent: In Earth’s early days, volcanic eruptions were ______.
5. Thick: Continental crust is _____than ocean crust.
6. Young: Ocean crust is _____ than continental crust.
7. Out: The crust forms the ____ layer of Earth.
8. Small: Some tectonic plates are ____ than others.
9. Deep: The upper mantle is _____ than the crust.
10. Dense: Basalt is ______than granite.
SRA2A
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