Exam 2

Question 1

Rocks turn into liquid at..

Answer 1

600-1200 centrigrade

Question 2

Magma vs lava

Answer 2

Magma is subsurface melt and lava is above surface. Magma is solid, liquid, gas, lava has NO gas

Question 3

Igneous

Answer 3

Cools extrusive (fast) and intrusive (slow), Magma forms from platonic

Question 4

Magma comes out at…

Answer 4

1200 centrigrade

Question 5

Volatiles

Answer 5

Cause rocks to melt at lower temp. Dry Hawaii: 600, Wet: 1200

Question 6

Geothermal gradiant

Answer 6

increase in temp w/ depth. Crust temp increases 25c/km

Question 7

Silica Compostions

Answer 7

Felsic: 70% SiO2 - 600C - Peanut butter
Intermediate: 60% SiO2
Mafic: 50% SiO2 - 1200C - Ketchup
Ultramafic: 40% SiO2
Represents everything in igneous world

Question 8

Differentialiation

Answer 8

Source rock melts from mafic to mafic
Partial melting
Assimilation: deep magma rising
Fractional crystalization

Question 9

Viscocity

Answer 9

Depends on temp, volatiles, silica
Hotter: low viscosity
More volatiles: lower viscosity

Question 10

Magma into rock (2 ways)

Answer 10

Planar vs Tubular shape

Question 11

Tabular intrusions

Answer 11

Uniform thickness
traced laterally
Sill: parallel to rock surface
Dike: Crosscuts rock fabric

Question 12

Sedimentary Rocks

Answer 12

Earth is covered by thin veneer of sediments
Caps meta. & Igneous “basement”
Varies in thickness from 0 to 20km

Question 13

Sedimentary weathering

Answer 13

process that breaks up sedimentary rocks
Physical: Mechanical breakage/ disintigration
Chemical: decomposition by reaction with water/oxygen
Occurs at the surface

Question 14

Types of weathering

Answer 14

Jointing = cracks in rock
frost wedging - freezing of ice increases 9% in volume, stronger than rocks
Root wedging = tree roots pushing rocks
Salt wedging - salt crystals grow between grains
Animal activity

Question 15

Chemical weathering (oxydation)

Answer 15

Resistant A –> Weak B
Dissolving material
Oxydation = Metal loses electron (rust)
Wustite (A) into Hematite (B)

Question 16

Chemical weathering (Hydration)

Answer 16

absorption of water into mineral structure
-volume increase
-clay
-between layers (mica), could increase volume 4x

Question 17

Rate of sedimentary weathering

Answer 17

Corners weather fastest (3 sides of attack)
Edges weather moderately (2 sides)
Flat weathering is slow (1 side)
Cubes have spheroidal weathering
Planar failure more effective than blocky breakage
Rate of weathering dependent on rock type

Question 18

Regolith vs Soil

Answer 18

Regolith are sediments that stay in place, soil are sediments that support life

Question 19

Soil profile

Answer 19

vertical sequence of layers
zone of leaching (upper soil profile), ions from chemical weathering
Climate controlled (temperate is best)

Question 20

Clastic sedimentary rocks

Answer 20

Through all types of sed.
Grain size decreases from source
Start as large and angular, poorly sorted to well, maturity increases with distance

Question 21

Cementing sediments

Answer 21

glueing together, usually quartz

Question 22

Limestone and carbonate

Answer 22

Limestone - CaCO3 shells remain
Carbonate grains accumulate in carbonate factory (ocean)
Ca,Mg,CO2 enter ocean

Question 23

Organic sediments

Answer 23

From organic carbon
Coal - altered remains of fossil vegetation
Oil Shale

Question 24

Sedimentary structures

Answer 24

Bedding –> changed conditions
Location of sediments differs in energy regime and ecosystem

Question 25

Marine environment = sediments deposited below sea level

Answer 25

Delta = River flow stops Shallow marine = limestone

Question 26

Metamorphic rocks

Answer 26

Change in temperature and pressure WITHOUT melting No weathering, occurs in solid state Creation of foliation and unique textures

Question 27

Protolith

Answer 27

Parent rock to a metamorphic rock Protolith of marble is limestone, Quartzlite is sandstone

Question 28

Temperatures of Igneous, Sedimentary, and Metamorphic through change

Answer 28

Igneous: 800C to 1300C Sedimentary: 40C to 200C Metamorphic: 200C to 800C

Question 29

Pressure increase

Answer 29

270 to 300 bars/km

Question 30

Shale to Gneiss

Answer 30

Mud (sediment) Shale (protolith) - Slate (low grade) - Phyllite - Schist (mid grade) - Gneiss (high grade) - Magma (igneous)

Question 31

Volcanos

Answer 31

SiO2 is everything (40-70%) Eruptions: Mt. Vesuvius, Pompeii, Herculonium

Question 32

Types of eruptions

Answer 32

Lava flow: molten rock over ground Pyroclastic debris - fragments blow out of volcano Volcanic gases: vapor exits Pahoehoe - Ropey flow A'A' - blocky flow, jagged more SiO2 - more viscous

Question 33

Pyroclastic flow vs Lahar

Answer 33

Pyroclastic - Dry and hot (1000C) Lahar flow - Cold and wet - cement slurry

Question 34

Partial melting

Answer 34

some parts of a rock melt faster than other

Question 35

Porphoritic

Answer 35

2 stage history with slow cooling and coarse grain crystals, fast explosion cooling

Question 36

Planetismal and meteoritic accretion

Answer 36

Adding material to a crust, gradual accumulation. Radioactive minerals Gravitational composition Why the Earth is hot on the inside!

Question 37

Plutons

Answer 37

Magma chambers cools to create sills (goes with rock layers) and Dikes (Perpendicular up and down)

Question 38

Igneous types of activity

Answer 38

Hotspots (mafic), convergent (felsic), divergent (Felsic)

Question 39

Dissolution

Answer 39

Halite, Calcite, gypsum Acid rain enhances effect

Question 40

Hydrolysis

Answer 40

Water takes away Cations in Silicate minerals Iron rusts