Transcript Rocks - Dallastown

April 27th Review
Drill: You find an igneous rock with
both coarse and fine grains. Describe
how this rock could have formed.
Objective: SWBAT review basic
concepts of the Rock Cycle in order
to prepare for the test.
Rocks
Igneous: Formed by molten material
either lava or magma.
Sedimentary: Created from
compaction and cementation of
layers of sediment and remains of
organisms.
Metamorphic: When a rock
undergoes extreme heat and
pressure causing it to change forms.
Sedimentary Rocks
Formed over millions of years.
Compaction: Pressure from layers
(and/or oceans) above.
Cementation: Minerals dissolved to
form materials that bind the
sediment together.
****Fossils normally found in this
type of rock.
****Typically rock forms in layers
Types of Sedimentary Rocks
Clastic: Larger pieces of sediment
that form rocks under pressure.
Organic: Rocks formed from living
materials
Chemical: Rocks that are “glued”
together through mineral solution.
Comparing Rocks
Texture:
Grain Size
Coarse vs. Fine
Grain Shape
Smooth & rounded
Rough & jagged
Grain Pattern
Flat layers
Wavy, swirling
Rows of beads
No pattern
No Visible Grain
Mineral
Composition:
Microscope
Acid test
Magnetic
Origin:
Igneous
Sedimentary
Metamorphic
Igneous
Formed from volcanic material
Intrusive: Formed from magma in the
Earth
Extrusive: Formed from lava on top
of the layers.
Grain size is determined by cooling
rate.
Metamorphic Rocks
Form from existing rock exposed to
extreme heat and pressure.
Folliated: Rock arranged in layers or
bands.
Non-folliated: Random pattern
Contact Metamorphism: Rock comes in
contact with an intrusion of magma
Fault metamorphism: Rock exposed to
extreme pressure from plate movement.
Rock Cycle
Rocks can change from one type to
another through a series of events.
Weathering and Erosions – Sediment
– Compaction/Cementation =
Sedimentary rocks.
Melting – magma – cooling = Igneous
rock
Extreme Heat and Pressure =
Metamorphic