Download Classifying Rocks

Classifying Rocks
• Geologists observe the rock’s _____,
_______ and its _______ _________.
• The size of the _____ of a rocks
defines its texture as ____ or ______,
and maybe _____.
• Rough texture results from _____
grains, smooth texture results from
_____ grained rocks.
• When the rock has no grains it is ____,
this results from quick cooling.
Some classical examples...
• Granite is formed by four basic _______.
• _______, _____, Feldspar and Hornblende.
• Each _______ may be present in different
proportions in different places on Earth.
• The different _____ sizes and minerals will
create an enourmous variety of ________.
• Sedimentary rocks may have ______ or
______ grains, like ________ and _______.
• Metamorphic rocks may show ______
patterns or the absence of patterns, like
_______ and _________.
Classifying By Origin
• Originate from magma: _______ rocks
form from the cooling of magma or lava.
• Originate from sediments: ______ rocks
form by erosion, deposition, compaction
and cementation.
• Originate from tremendous heat,
pressure or chemical reactions:
__________ rocks form when any rock,
mostly underground, suffers heat,
pressure or chemical reactions
Igneous Rocks
• Igneous rocks are classified by their
_____, ______ and _____ ________.
• Extrusive igneous rocks cool at the
______; basalt, obsidian, and pumice.
• Intrusive igneous rocks cool under the
______; granite.
• A porphyritic texture is formed when
larger crystals scatter on a background
of much _______ crystals.
• Lava with low silica forms ____ rocks,
high silica forms ______-colored rocks.
Sedimentary Rocks: Clastic Rock
• When rock fragments are ______
together clastic rocks are formed.
• Shale is formed by particles of _____,
sandstone is formed by ______.
• Conglomerate (____ edges) and Breccia
(______ edges) contains a mixture of
fragments of different sizes.
The Process of Sedimentation
• Describe here how sedimentary rocks
form:
• 1.
• 2.
• 3.
• 4.
• 5.
• Sedimentary rocks may be _____,
______, and ________.
Organic Rock
• When the remains of _____ and plants
are deposited in thick ____ and petrify.
• Organic means that once these pieces
were ____ of a _______ thing.
• Coal (swamp plants and animals _____ in
water) and limestone (hard shells) are
some of the organic __________ rocks.
Sedimentary Rocks: Chemical Rock
• When minerals that are _________ in a
solution and _____________.
• Halite, gypsum and some forms of
____________ are chemical rocks.
• Limestone is very important to _____
iron and in making __________.
Scketch here: Tufa Towers of
Mono Lake, California
(slide 23 Rocks PPP)
Metamorphic Rocks
• _____ and _______ deep beneath
Earth’s surface can ______ any rock
into metamorphic rock.
• To classify metamorphic rocks
geologists look at the__________of
the rock’s grains.
• Grains arranged in _________ layers or
bands are called foliated; like Gneiss
and slate.
• Grains _________ arranged are called
non-foliated; like quartzite and marble.
Sketch here: Granite  Gneiss
(Rocks PPP slide 25)
Sketch here: Shale  Slate
(Rocks PPP slide 26)
Sketch here: Sandstone  Quartzite
(Rocks PPP slide 27)
The Rock Cycle
• Forces _______ Earth and at the
_________ produce a rock cycle that builds
and destroys, and ________ the rocks in the
crust.
• The rock cycle can follow many___________
pathways.
• Plate movements drive the rock cycle
_______ rocks back into the mantle, where
they _____ and become magma again.
• Plate movement also cause the _______,
__________, and ________ of the crust
that move rocks through the rock cycle.
Sketch here: The Rock Cycle
(Rocks PPP slide30)