rock notes i. what is a rock? rock - two or more minerals (found in the earth’s crust) bound...
Post on 14-Dec-2015
220 Views
Preview:
TRANSCRIPT
I. What is a rock?
Rock - two or more minerals (found in the earth’s crust) bound together in a solid form
II. Rock types
B. Metamorphic rocks- formed when rocks that already exist are changed by heat and pressure into new kinds of rocks.
II. Rock types
C. Igneous rocks- formed by cooling and hardening of hot molten rock from inside the Earth. Hot molten rock from inside the earth is called magma.
III. Igneous Rock Formation
A. Magma - molten (liquid) rock found beneath the earth’s surface. Intrusive Rock - rock formed underground when magma cools
III. Igneous Rock Formation
A. From Magma (Intrusive )
Cooled slowly
Deep Shallow
Large/Coarse Small Crystals Crystals
III. Igneous Rock Formation
B. Lava - magma on the surface of the earth Extrusive Rock - rock formed on the surface when lava cools
III. Igneous Rock Formation
B.From Lava (Extrusive)
Cooled quickly
Surface
Fine Crystals Glassy Rocks
IV. Igneous Rock CharacteristicsA. Felsic (feldspar and silica--Granitic, Continental)
• Chemistry: High percent of silicates (Si) and water. Low percent of iron (Fe), calcuim (Ca), & magnesium (Mg)
• Color: Light colored minerals
• Viscosity: More viscous (Thick--Low temperatures and slow flowing)
• Trapped gases: H2O, O, CO2, H2, CO, H2S, SO2
• Density: Low level (high gas content)
IV. Igneous Rock CharacteristicsB. Mafic (Magnesium and iron--Basaltic, Oceanic)
• Chemistry: Low percent of silicates (Si). High in Ca, Fe, Mg.
• Color: Dark colored minerals
• Viscosity:Low viscosity (thin--high temperature and more fluid)
• Trapped gases: fewer present
• Density: Higher level (few gases)
IV. Igneous Rock CharacteristicsC. Andesitic (Intermediate, Continental)
• Chemistry: Intermediate percent of silicates (Si). Intermediate in Ca, Fe, Mg.
• Color: Intermediate colored minerals
• Viscosity: Intermediate viscosity (fluidity)
• Trapped gases: Intermediate amounts present
• Density: Intermediate level
IV. Igneous Rock Characteristics (D. Review)
A. Felsic B. MaficMostly light Mostly dark
colored minerals colored minerals
[ Si] [Ca, Fe, Mg] [ Si] [Ca, Fe, Mg]
C. Andesitic
Contain light and dark minerals
Intermediate levels of [Si, Ca, Fe, Mg]
IV. Igneous Rock Characteristics (D. Review)
A. Felsic Dissolved B. Mafic Dissolved Gases Gases
Thick & Slow Thin & Fast
Hard For Gases Gases Escape To Escape Easily
Explosive Eruptions “Gentle” Eruptions
Note: Dissolved Gases Include H2O, S, CO2, H2, CO, H2S, SO2
Extrusive
IntrusiveSmall crystals
Large crystals
IV. Igneous Rock Characteristics (D. Review)
NO crystals
Darker colored rocks
Lighter colored rocks
VI. How we study rocks
A. Color: Lightness/darkness indicates chemistry. Darker rocks tend to have more iron (Mafic), lighter rocks have more silicon (Felsic).
B. Crystal size: Can be measured in millimeters using a hand lens/microscope and ruler. Larger crystals need more time to form and are found in rocks that cool slowly (intrusive).
VI. How we study rocks
C. Density: mass (g) ÷ volume (ml or cm3).
More dense rocks formed from magma that originates deeper in mantle (less explosive volcanoes) and contain
fewer gases (Mafic).
Less dense rocks formed from magma that originates from outer mantle (more explosive volcanoes) and contain more trapped gases due to interaction with ocean water (Felsic).
=(C4/D4)
top related