When a molten rock material cools and solidifies it becomes an igneous rock.
Igneous comes from word “ignis” meaning fire.
Igneous Rocks are formed by melting, cooling, and crystallization of other rocks.
Igneous Rocks are formed by crystallization from a liquid, or magma. They include two types:
Extrusuve igneous rocks cool quickly and as a result these rocks are fine grained or has lack of crystal growth.
Intrusive igneous rocks are forms from magma that cools slowly and as a result these rocks are coarse grained.
Igneous Rocks are formed by crystallization from a liquid, or magma. They include two types:
Extrusuve igneous rocks cool quickly and as a result these rocks are fine grained or has lack of crystal growth. Cooling time: seconds to months. Texture: invisible or microscopic grains
Intrusive igneous rocks are forms from magma that cools slowly and as a result these rocks are coarse grained. Cooling time: thousand of years. Texture: small-to-medium grains.
Plutonic- Cooling time: millions of years. Texture: large grains.
Types of rocks
Igneous
Sedimentary
Metamorphic
Igneous rocks
Formed by melting, cooling, and crystallization of other rocks
Formation of igneous rocks
1. Melting
2. Cooling
3. Crystallization
Where igneous rocks form
Along plate boundaries or mantle hot spots
At divergent boundaries like mid-ocean ridges
At subduction zones
At continental-continental convergent boundaries
Texture
Describes the appearance of an igneous rock based on the size, shape, and the arrangement of its interlocking crystals
Igneous rock textures
Glassy
Aphanitic
Phaneritic
Composition refers to the elements in the magma that is directly affects the kind of mineral that is formed when magma cools. The mineral color varies with silica (SiO2) content
Magma composition
Felsic
Intermediate
Mafic
Plutonic vs volcanic
Plutonic igneous rocks form by slow cooling below ground
Volcanic igneous rocks form by fast cooling above ground
Sedimentary rocks
Formed by weathering, erosion, deposition, compaction, and cementation of other rocks
Formation of sedimentary rocks
1. Weathering
2. Erosion
3. Deposition
4. Compaction
5. Cementation
Types of sedimentary rocks
Clastic
Chemical
Organic
Clastic sedimentary rocks
Derived from mechanical weathering and breakdown of rocks into smaller pieces
Clastic sedimentary rocks
Conglomerate
Sandstone
Mudrock
Chemical sedimentary rocks
Form when dissolved minerals come out of solution
Organic sedimentary rocks
Composed of materials formed by the activity of living organisms
Subduction zones occur whenever a dense oceanic plate is subducted underneath another oceanic or continental plate.
Glassy igneous rocks have no crystal structure, and probably formed by very rapid cooling (such as on the surface of a lava, or when a lava enters the water.)
Aphanitic rocks have no visible crystals, and probably formed by fast cooling above ground.
Phaneritic rocks have visible crystals, and probably formed by slow cooling below ground.
Light-colored rocks are silica-rich minerals.
Dark-colored rocks are silica-poor minerals.
Felsic magma rock
High silica-rich igneous rocks.
It has light-colored igneous rocks with few dark minerals.
65% SiO2, low in Fe, Mg, Ca, high in K, Na.
Intermediate magma rock
It has roughly even mixtures of felsic minerals and mafic minerals.
55%-65% SiO2, intermediate. in Fe, Mg, Ca, Na, K
Mafic magma rock
It has low silica content.
It has dark-colored igneous rocks with few light minerals.
< 55% SiO2, high in Fe, Mg, Ca, low in K, Na
Identify
A) Rhyolite
B) Andesite
C) Basalt
D) Granite
E) Diorite
F) Gabbro
G) Felsic Rocks
H) Intermediate
I) Mafic
J) Volcanic
K) Plutonic
Plutonic rocks are formed when magma cools and solidifies underground. Volcanic rocks are formed from lava that flows on the surface of the Earth and other planets and then cools and solidifies.
Classification
Physical weathering is the breakdown of rocks by temperature changes and physical processes such as frost, water, and wind
Chemical weathering is the breakdown of rocks through chemical reactions between the rock and its environment
Biological weathering is the breakdown of rocks by living organisms.
Erosion: the process of eroding or being eroded by wind, water, or other natural agents
Weathering is the process of breaking down rocks and minerals into smaller pieces by water, wind, and ice.
Erosion is the process by which natural forces move weathered rock and soil from one place to another. Gravity, running water, glaciers, waves, and wind all cause erosion. The material moved by erosion is sediment
Clastic sedimentary rocks derived from mechanical weathering which involves the breakdown of rocks into smaller ones at the surface of the crust.