what are rocks? rocks are a naturally occurring solid ......rocks are a naturally occurring solid...
TRANSCRIPT
WHAT ARE ROCKS? ROCKS are a naturally occurring
SOLID MIXTURE of one or
more minerals and organic
matter.
Rocks are ALWAYS changing.
How do we
classify Rocks?
Formation (where and how
the rock was formed)
Texture (grainy, glassy)
Composition (what
minerals make up the rock)
What are Igneous
Rocks?
From the Latin word igni (fire)
Form from the cooling of
molten rock (lava and magma).
The most abundant type of
rock.
Classified according to their
origin and composition.
Classification 1
ORIGIN— Where are Igneous Rocks are formed
How does Extrusive Igneous Rocks form?
(Think Exit)
Extrusive Rock is formed from lava erupted onto Earth’s surface.
Exits the Earth- thus it is lava that is cooling.
Cools quickly before large crystals can form.
Will have fine-Grained, small crystals.
Extrusive rocks are smooth
Ex. (Basalt)
How does
Intrusive
Igneous Rocks
form?
(Think inside)
Intrusive Rock is formed when magmahardens beneath Earth’s surface.
Magma cools slowly inside of the earth.
Slow cooling causes the formation of Coarse-Grained rocks with large crystals.
Intrusive rocks usually have a rough texture.
Ex. Granite
What is Lava?
What is Magma?
molten material found on the surface of the earth.
molten material found beneath the surface of the earth.
• Obsidian has a glassy texture
• Rhyolite has a fine-grained texture
What does Mafic
describe?
What does Felsic
describe?
Mafic describes dark colored igneous rocks.
Mafic rocks have a low amount of silica, but a higher amount of iron, magnesium, or calcium.
Felsic describes light colored igneous rocks.
Felsic rocks contain a high amount of silica.
What are
sedimentary
rocks?
Rocks made from sediments that are pressed or cemented together or when sediments precipitate out of a solution.
Sedimentary rocks represent 7% of the Earth’s crust, but they cover 70% of the Earth’s surface.
There are 3 types of sedimentary rock.
Sedimentary rocks are fossil-carrying rocks.
What are
sediments ?
Rock fragments, mineral grains, animal & plant remains-shells, bones, leaves, stems
Where do
Sedimentary rocks
form?
Visual Clues that it
is sedimentary rock.
Form at or near the surface of the earth = no internal heat
The rock will have layers (strata)
What are Strata?
Horizontal layers found in sedimentary rocks.
Layers at the top are the youngest (newest), layers at the bottom are older.
Newer layers
Older layers
How does
Sedimenta
ry rock
form?
W
Weathering
the breaking down of material by
wind, water, ice, sunlight, & gravity
E
Erosion Movement of sediment
D
DepositionWhere the sediment is deposited.
C
Compaction
As new layers of sediment occur,
the weight of the new layers can
squeeze the older sediment tightly
together. (mush)
C
Cementation
Dissolved minerals flow between
the particles and glue them
together
Classification 2
Formation— How are Sedimentary rocks formed.
There are 3 types of Sedimentary Rock
What are
the three
types of
sedimentary
rock?
Clastic: (Rock & mineral fragments compacted & cemented together)
Chemical: (solutions of dissolved minerals & water)
Organic: Form where the remains of plants and animals are deposited in thick layers (Contain remains, fossils of ocean animals)
What is
metamorphic
rock?
Rocks that have changed due to intense temperature and pressure
“Meta” means “change” and morphosis means “form” in Greek
Igneous, sedimentary and other metamorphic rocks can change to become metamorphic rocks.
What occurs
in the Earth
to change
these rocks?
Pressure from overlying rock layers.
High heat, but not enough to melt the rock.
Rocks may be flattened or bent or atoms may be exchanged to form new minerals.
How are
metamorphic
rocks
classified?
Foliated—mineral grains are flattened and line up in parallel bands.
Non-Foliated—No bands are formed.
Foliated Non Foliated