Key to Cornell notes for Understanding Rock
1. Rock
2. How rocks are
important
A mixture of minerals
Rocks have properties that make them useful for many different things
today. Because rocks are strong and can support heavy loads they are
often used for buildings and other structures. Many rocks are beautiful
and so are used for decorative purposes.
3. Rock Cycle
A series of events that don’t take place in any particular order, in which
any rock can change into any other type of rock depending on the
conditions it is exposed to in nature.
4. How each type of
rock forms
Sedimentary: Through weathering, sediment is created, which is eroded
and deposited in a horizontal layer, then buried by more layers of
sediment, which compacts it, meanwhile, minerals fill in the spaces
between the sediment grains to form a cement.
Metamorphic: Rocks undergo great pressure usually from some sort of
deformation, with the pressure often the rock is heated, but still remains a
solid, and causes the minerals in the rock to change-either their chemical
composition and/or their form.
Igneous: Rocks that melt form liquid lava or magma which cools and
solidifies either above ground of underground.
5. Can every type of
rock change into
every type of rock?
Yes if it undergoes the specific process that forms a particular type of
rock, it can change in the rock cycle into a different rock. This means that
sedimentary rock can change directly into metamorphic rock, or it could
change directly into an igneous rock if it underwent the process that
formed those particular types of rock.
6. How texture and
composition help
scientists
The composition and texture help scientists know what the history of the
rock is and how it formed, so to understand the events that occurred in
that place.
7. Texture
The sizes and shapes of the grains making up the rock
8. Composition
The types of minerals making up the rock
Key to Cornell notes about Igneous Rocks
1.
What determines the
texture of Igneous rock
The size of the grains is determined by how fast the rock
cools. Fast cooling lava on the surface of the earth forms
fine-grained rock, while slow cooling magma underground
forms coarse-grained rock.
2. Felsic vs. mafic rock
Felsic rock is composed of continental crust, so is light in
color and less dense, while mafic rock is composed of oceanic
crust so is dark in color and more dense.
3. Intrusive igneous rock
Formed underground, as shown by its coarse-grained texture
4. Examples of intrusive
Dike, sill, pluton, batholiths, and laccolith
igneous rock formations
A sill forms when magma goes between the rock layers
Laccoliths form when enough magma flows between the
rocks layers, they are pushed up.
A dike forms when magma flows in cracks that cut through
rock layers
A pluton is balloon shaped intrusions
Batholiths form when many plutons converge into one
immense pool of magma deep underground.
5. Examples of intrusive
igneous rock
Felsic: Granite, and diorite, pegmatite
Mafic: gabbro
6. Extrusive rock
Igneous rock that formed when lava or volcanic materials
cooled above ground. It is either a crystalline rock with a very
fine-grained texture (the grains can’t be seen), or it is glassy
(containing no grains), or it is made of volcanic ash with gas
escape holes throughout it.
7. Examples of extrusive
Volcanoes themselves are made of extrusive rock, also
igneous rock formations extrusive formations are lava plateaus
Photo of a lava plateau
8. Examples of extrusive
igneous rocks
Felsic: Rhyolite, Andesite, pumice
Mafic: Basalt, Diabase (medium) komatite, obsidian, tuff