Rocks 1 Rocks in Relation to Minerals Many kinds of rocks are - - PowerPoint PPT Presentation
Rocks 1 Rocks in Relation to Minerals Many kinds of rocks are composed of minerals Granite ; mica , feldspar and quartz Monomineralic; rocks that are composed of only one mineral . Limestone Calcite Polymineralic; rocks
1
Many kinds of rocks are composed of
minerals
Monomineralic; rocks that are composed of
Polymineralic; rocks that are composed of two
There are almost 3,000 types of minerals
2
Plagioclase Feldspar 38%
Potassium Feldspar 12% Quartz 12%
Clays 4.6%
3
rocks.
Rocks are classified based on their
method of formation (origin).
3 Rock Groups
4
Rocks that usually form in horizontal layers;
from the accumulation of sediments, organic matter, or chemical precipitates
Silt Sand Silt Clay Clay Silt
Pressure Pressure
Time Silt
Sandstone Shale Siltstone Shale
Layers of sediment deposit and accumulate Pressure/weight squeezes lower layers Sediment is compacted and cemented into rock
5
Clastic: form from rock particles and sediment
that are pressed and cemented together.
(calcite) After Deposition Compaction Cementation
6
7
Chemical: form from minerals dissolved
in water; which settle-out/precipitate.
evaporates
8
Organic: form from the accumulation of
plant/animal matter that undergoes a transformation into rock.
9
10
They are composed of
rock fragments or
Can contain a wide
range of particle/ sediment sizes.
Some have a uniform
sediment size; due to sorting during deposition
11
12
Some rocks are
from plant and animal remains (fossils)
Usually form in
horizontal layers called strata or beds
13
Form from the cooling and solidification
magma.
the crystals of different minerals form a rock.
inter-grown crystals of different sizes, shapes, and composition
14
Extrusive/Volcanic:
surface.
Intrusive/Plutonic:
Earth.
15
Environment of Formation Extrusive (Volcanic) Intrusive (Plutonic)
Rate of cooling
Very Fast
Fast Slow
Grain Size Non-crystalline Less than
1mm 1mm or larger
Texture
Glassy Fine Coarse
Examples
Obsidian Basalt
Rhyolite Granite Gabbro
16
Location in Earth’s crust effects the
cooling rate
No Crystals Very Fast Cooling Small Crystals Fast Cooling Large Crystals Slow Cooling
Crystal Size Rate of Cooling
17
18
Rocks that form from pre-existing rocks
(sed., ign., meta.) that have been changed.
due to contact with extreme heat (magma),
regions where the deeper bedrock is exposed due to weathering and erosion
Metamorphic Rock
Pressure
Heat
19
Conditions that cause rocks to undergo metamorphism
Contact Metamorphism
through direct contact with the magma or lava
Regional Metamorphism
extreme pressure applied during mountain building events
20
Recrystallization - Environments within the
crust with high temperatures and high pressure; cause rocks to change by recrystallization.
sedimentary rock, and from the “old” crystals in an igneous rock.
21
Non-Foliated/Unfoliated
in layers; do not break in layers/sheets
Foliated
parallel “bands.”
22
Banding
produces thicker bands of alternating crystals
extreme pressure exerted on the rock.
Mineral Alignment
layers.
23
Metamorphic Rock
F
a t e d
Slate Schist Gneiss
U n
a t e d
Marble Quartzite Anthracite Coal
Original Rock Type
Shale Sedimentary Slate Metamorphic Granite Igneous Limestone Sedimentary Sandstone Sedimentary Bituminous Coal Sedimentary
24
The Rock Cycle
shown by the processes in the rock cycle.
25
26
Rocks Sedimentary Igneous Metamorphic Clastic Sediment Organic Bioclastice Crystalline Chemical Conglomerate Sandstone Siltstone Shale Bituminous Coal Limestone Chalk Limestone Rock Salt Rock Gypsum Intrusive Plutonic Granite Gabbro Diorite Pumice Obsidian Basalt Rhyoltie Marble Quartzite Anthracite Coal Slate Schist Gneiss Foliated Unfoliated Extrusive volcanic
Stonehenge
Grand Canyon; layers of Sedimentary rocks
Pyramids; Limestone
27