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Rocks and the Rock Cycle
Earth Science – Competency Goal 1.02
Rocks and Rock Cycle – Three Major
Types
 Three
major Rock types.
Igneous
Sedimentary
Metamorphic
Rocks and Rock Cycle – Igneous

Igneous – Latin Term – “From Fire”
 Igneous rocks form when magma cools and
hardens.
 Magma is called lava if it cools at the Earth’s
Surface
2 major types Igneous
Intrusive – Magma forms and intrudes rocks
beneath the Earths
surface
Extrusive – The rapid cooling of magma at the
Earth’s Surface.
Rocks and Rock Cycle – Igneous



Mineral Composition –
 Granite Family (Felsic) Rich in silica.
 Basalt Family (Mafic) Rich in iron.
Texture – Extrusive
 Fine grained minerals – cool quickly, Pumice
 No mineral composition - Obsidian
Texture - Intrusive
 Large minerals – cools slowly beneath the
Earth and then more rapidly as it nears the
surface – Granite. Page 178
Rocks and Rock Cycle – Sedimentary

Sedimentary – Compaction and cementation are the
process behind the formation of this rock type.
 Clastic – separate fragments of rocks are
compacted to form one.
 Chemical – forms from minerals that have
dissolved in water over time
 Organic – forms from the remains organismslimestones, coal, fossils.

Features – stratification, layering, ripple marks, mud
cracks, salt casts.
Rocks and Rock Cycle – Metamorphic


Rocks deformed from heat, pressure, and hot
fluids can certain minerals to change into
other chemicals.
Types of Metamorphic Rocks.
 Unfoliated rocks no banding
 Foliated Rocks formed with a banding look
– alternating dark and light bands.
 Extreme pressure will flatten them
 Different density will sort minerals