Geomorphology

Question 1

Direct Sources of the Interior

Answer 1

1. Mining: Gaut (South Africa) is the deepest mine (3.8KM)
2. Drilling: Kola Superdeep (Russia) is the deepest drill (12KM)
3. Volcanic Eruptions

Question 2

Indirect Sources of the Interior

Answer 2

1. Variations of T, P, ρ with depth
2. Gravity
3. Magnetic Field
4. Meteors
5. Gravity Anomaly (Variation in gravity with change in mass)
6. Seismic Waves

Question 3

About P - Waves (Body)
(a) Which direction they travel?
(b) Which type of Stress?
(c) Can propagate through?
(d) Depth of penetration?
(e) Velocity of P - wave in different medium
(f) Faster in oceanic crust (or) continental crust?

Answer 3

(a) Longitudinal - Along the wave
(b) Compressional Stress
(c) Solid, Liquid, Gas
(d) Deep into the Earth
(e) Solid > Liquid > Gas
(f) Oceanic Crust (Density of oceanic crust is higher than continental crust)

Question 4

About S - Waves (Body)
(a) Which direction they travel?
(b) Which type of Stress?
(c) Can propagate through?
(d) Depth of penetration?

Answer 4

(a) Transverse - Perpendicular to the wave
(b) Shear Stress
(c) Only Solid
(d) Deep into the Earth

Question 5

About L - Waves (Surface)
(a) Which direction they travel?
(b) Can propagate through?
(c) Depth of penetration?

Answer 5

(a) Horizontal (or) Side to Side of Earth’s surface
(b) Only Solid
(c) At Earth surface only

Question 6

Velocity of P S L waves comparison

Answer 6

P > S > L

Question 7

Generally, Velocity of waves ______ with density?

Answer 7

Velocity of waves ∝ Density

Question 8

P wave shadow zone occurs in?
If it can pass through all mediums then why does this occur?

Answer 8

± 105° - 142°
P - waves are refracted when they pass through the transition between semi - solid mantle and liquid outer core

Question 9

S wave shadow zone occurs in?

Answer 9

± 105° - 180°

Question 10

What happens to density, temperature, pressure with increasing depth?

Answer 10

T P ρ ∝ Depth

Question 11

Average Density of Earth = ?
Density at Surface = ?
Density at the core = ?

Answer 11

Average Density of Earth = 5.5 g/cm³
Density at Surface = 2.7 g/cm³
Density at the core = 13 g/cm³

Question 12

Major elements of the crust order

Answer 12

O2 > Si > Al > Fe > Ca > Na > K > Mg

Question 13

Six major family groups of minerals are?

Answer 13

1. Silicates (Majority = >90%)
2. Oxides
3. Sulfides
4. Sulfates
5. Carbonates
6. Halides

Question 14

Types of Rocks - Define formation process, Illustrate with examples

Answer 14

1. Igneous Rocks: Solidified from Magma (Eg) Gabbro, Basalt, Granite
2. Sedimentary Rocks: Deposition of fragments of rocks. Layered non - crystalline rocks (Eg) Sandstone, Shale, Conglomerate
3. Metamorphic Rocks: Formed from Igneous rocks under high T/P and from Sedimentary rocks by weathering and erosion. Recrystallization and reorganization of minerals (Eg) Gneissoid, Slate, Schist, Marble, Quartzite

Question 15

Magma under rapid cooling results in which type of igneous rocks?

Answer 15

Fine grained crystalline - small size - soft

Question 16

Magma under slow cooling results in which type of igneous rocks?

Answer 16

Coarse crystalline - large size - hard

Question 17

Relation between Toughness and Depth of igneous rocks

Answer 17

Toughness of Igneous Rocks ∝ Depth

Question 18

Igneous rocks toughness variation with latitude?

Answer 18

In higher latitudes -> Cools down rapidly -> Fine grained crystalline - soft - brittle in nature (Relatively)

In lower latitudes -> Cools down slowly -> Coarse crystalline - hard formation

Question 19

Which of the only rock(s) is having stratified layers?

Answer 19

Sedimentary Rocks

Question 20

Which only rock consists of fossils?

Answer 20

Sedimentary Rocks

Question 21

Types of Igneous Rocks

Related to the depth

Answer 21

1. Intrusive Igneous Rocks (Plutonic Rocks)
   Magma - Slow cooling - High Depth - Result: Hard and Large Rocks - Eg: Granite, Gabbro
2. Extrusive Igneous Rocks (Lava/Volcanic Rocks)
   Magma - Rapid cooling - Low Depth - Result: Fine Grained and Soft Rocks - Eg: Bassalt
3. Hypabyssal (or) Dyke Rocks (or) Intermediate Rocks
   Magma - Neither slow nor rapid - Near surface - Result: Semi crystalline - Eg: Micro granites, Porphyry, micro diorites, dolerites

Question 22

Acidic rocks v/s Basic Rocks Differences

Answer 22

1. Silica content: A > B
2. A - Si dominant & B - Mg dominant
3. A - Lighter in color & B - Darker in Color
4. A - Hard, Compact, Massive & B - Relatively, less hard, more prone to weathering
5. (Examples) A - Granite, Quartz, Feldspar & B - Basalt, Gabbro, Dolerite

Question 23

Types of Sedimentary Rocks

Answer 23

1. Mechanically Formed (Clastic Rocks)
   Accumulation of rock fragments - cemented together (Eg) Sandstone, Conglomerate, Limestone, Mudstone, Claystone, Shale, Loess, etc.
2. Chemically Formed
   Formed by chemical precipitation from sea water (Eg) Chert, Limestone, Halite, Potash, Nitrates, etc.
3. Organically Formed
   Formed from the remains of the dead plants and animals (Eg) Geyserite, Chalk, Limestone, Coal, etc.

Question 24

Types of Metamorphism

Answer 24

1. Dynamic Metamorphism
   Involves Mechanical disruption and reorganization
2. Thermal Metamorphism
   Involves Chemical alterations and recrystallization
   2.1. Contact Metamorphism
   2.2. Regional Metamorphism

Question 25

Find the type of the rock for the following and Name of Metamorphic Rock?

Limestone
Dolomite
Sandstone
Shale
Granite
Slate
Phyllite

Answer 25

Name of Rock - I/S/M - Name of M Rock

Limestone - S - Marble
Dolomite - S - Marble
Sandstone - S - Quartzite
Shale - S - Slate
Granite - I - Gneiss
Slate - M - Schist/Phyllite
Phyllite - M - Schist

Question 26

Other names of the following:
1. Igneous Rocks _____
2. Sedimentary Rocks _______

Answer 26

1. Igneous - Primary Rocks
2. Sedimentary - Detrital Rocks

Question 27

Some important rock forming minerals are?

Answer 27

1. Feldspar
2. Quartz
3. Bauxite
4. Cinnabar
5. Dolomite
6. Gypsum
7. Haematite
8. Magnetite
9. Amphibole
10. Mica
11. Olivine
12. Pyroxene