Unit #2: Rocks,

Minerals, and Resources

•Rock - a naturally formed solid piece of the Earth’s crust composed of a mixture of minerals

•All rocks have minerals.

• http://www.schooltube.com/video/503ca205aae459f47494/The-Rock-Cycle

•Rocks that contain 1 mineral are called monomineralic.

•Rocks that contain more than 1 mineral are called polymineralic.

Rock Types

• Igneous•Sedimentary•Metamorphic

Rock Classification• Rock are classified based upon how they form.

• Igneous rocks form from the cooling and solidification of molten rock.

• Sedimentary rocks form from fragments of other rocks, chemical precipitates, or organic remains.

• Metamorphic rocks form from other rocks that undergo intense heat and pressure but not melting.

Types of Molten Rock

• Lava - liquid rock at the Earth’s surface

• Magma - liquid rock beneath the Earth’s surface

http://www.youtube.com/watch?v=P5_4IImARPg&safe=active

Mt Etna, November 18, 2013

Types of Igneous Rock• Intrusive or Plutonic - form from magma - have larger crystals and a coarse texture

• Extrusive or Volcanic - form from lava - have smaller crystals and a finer texture

Composition

Mafic• Dark color, high density • Contains Magnesium(Mg) and Iron(Fe)

bearing minerals

Felsic• Light color, low density• Contains feldspar and silicate minerals• High aluminum(Al) content

Vesicles

• Tiny holes created by gases escaping from molten lava while it is cooling and solidifying

Igneous Rock

Coarse Texture in Gabbro

Fine Texture in Basalt

Extrusive Igneous Rock

Do Now

1. What three factors are used to identify igneous rocks?

2. What processes cause the formations of the following rock types? (Igneous, Metamorphic, Sedimentary)

3. Where do sediments come from?

Types Of Sediments

Clastic- Fragments of Other Rocks-Grain Size

Evaporties- Sea Water evaplorates leaving behind sediments. (Salt)

Precipitates- Chemical-Solutioning(ions)Biologic- Plankton, Diatoms

Biologic- Terrestrial– Plants/TreesMarine- Shells, Coral,

Stromatalites

Types of Sedimentary Rock• Clastic or Fragmental - form from the fragments of other rocks (sediment)

Stream Deposition

• Cause of deposition- Velocity Decreases

• Sediment characteristics effecting deposition–Size ––Shape-–density

Size:

Largest Particles Settle First

Shape:

Roundest Particles Settle First

Density:

The most dense particles settle first.

Horizontal SortingStream Flow

•Flow Widens

•Slower Water

Large, Round, Dense Sediment

Small, Flat, Lighter Sediment

Delta

The Yukon River Delta

Sedimentary Rock

Sedimentary Rock

Vertical Sorting

Small

Large

Types of Sedimentary Rock• Nonclastic - organic and chemical - form from organic remains (shells, etc.) or chemical precipitates

Types of Metamorphism

• Regional - heat and pressure are applied to a large area of rock in collision zones of the Earth’s tectonic plates

• Contact or Thermal - rock is “burned” due to heat from lava or magma

Types of Metamorphic Rock

• Foliated- have banded, striped, or layered minerals due to pressure applied during metamorphism

• Nonfoliated - do not have a banded, striped, or layered appearance

Foliation and Distorted Structure

Metamorphic Rock

Metamorphic Rock

Features in Igneous Rocks

• The faster the molten rock cools the smaller the crystal size in the resulting rock. Rock forming from lava have smaller crystals than rocks forming from magma

• Some igneous rocks have a glassy texture due to quick cooling.

• Some igneous rocks have holes called vesicles formed by gases escaping from lava.

Features in Sedimentary Rocks

• Fossils tend to occur only in sedimentary rocks.

• Some sedimentary rocks have fragments of other rocks (sediment) within them.

• Sedimentary rocks form in flat, horizontal layers called strata.

• Some sedimentary rocks form from evaporating sea water (evaporites).

Sedimentary Rock

• Some other features in sedimentary rocks are :

• Cross Bedding• Ripple Marks• Mud Cracks• Graded Bedding

Cross Bedding in Sandstone

Ripple Marks in Sand

Mud Cracks in Clay

Graded Bedding

Features in Metamorphic Rocks

• Some metamorphic rocks have a banded, striped, or layered appearance (foliation).

• Metamorphism can enlarge mineral grains or create new minerals.

• Metamorphism can increase the density of a rock.

• Some metamorphic rocks have a distorted or twisted rock structure created by intense pressure.

• Metamorphism causes changes in rock through recrystallization.

Distribution of Rock Types on the Earth

• Sedimentary rocks tend to be found in a thin layers at the Earth’s surface.

• Igneous and Metamorphic rocks tend to form in mountain ranges.

• The abundance of igneous and metamorphic rocks increase as you go deeper into the Earth.