Engineering geology lecture 1

Question 1

What is the definition of a mineral?

Answer 1

Naturally ocuring inorganic substance which has a definite chemical composition and presents an ordered atomic arrangement

Question 2

What is the definition of a rock?

Answer 2

An aggregate of one or more mineral, the nature and the properties of a rock are determined by the minerals in it and the manner in whcih the minerals are arranged relative to each other

Question 3

What rock is chrystallised from molten magma?

Answer 3

Igneous

Question 4

How are sedimentary rocks fromed?

Answer 4

From erosion on the Earth’s surface

Question 5

How are metamorphic rocks formed?

Answer 5

They are altered by heat and/ or pressure

Question 6

Which environment do Igneous rocks come from?

Answer 6

Underground, as lava flows

Question 7

What rocks are formed in deposition basins, mainly sea?

Answer 7

Sedimentary

Question 8

Where are metamorphic rocks found?

Answer 8

Mostly deep inside mountain chains

Question 9

What type of rock is described as a mosaic of interlocking crystals?

Answer 9

Igenous and metamorphic

Question 10

What is the texture of a sedimentary rock?

Answer 10

mostly granular and cemented

Question 11

Wnat is the structure of an ingeous rock?

Answer 11

massive (structureless)

Question 12

What is the structure of a sedimentary rock?

Answer 12

Layered, bedded, bedding planes present

Question 13

What is the structure of a metamorphic rock?

Answer 13

Chrystal orientated

Question 14

What type of rocks have uniform high strength?

Answer 14

Igneous

Question 15

How strong are sedimentary rocks?

Answer 15

Variable low, planar weaknesses present

Question 16

How strong are metamorphic rocks?

Answer 16

Highly variable

Can have planar weakness

Question 17

What are some main types of Igneous rock?

Answer 17

Granite
Granodiorite
Basalt

Question 18

What are some main types of Sedimentary rocks?

Answer 18

Sandstone
Limestone
Clay

Question 19

What are some main types of metamorphic rocks?

Answer 19

Gneiss
Schist
Slate

Question 20

What characteristics are helpful when dealing with minerals?

Answer 20

1. Colour
2. Lustre (appearance/ reflectance)
3. Form (shape/ group/ clustering)
4. Hardness (resistance to abrasion)
5. cleavage (preferential split)
6. Fracture (nature of broken surfaces - lack of cleavage)
7. Tenacity (response upon sudden impact i.e. malleable vs brittle)
8. specific gravity

Question 21

What are the 2 different classifications of minerals?

Answer 21

1. Silicate minerals

2. non - silicate minerals

Question 22

What kind of mineral is olivine, and what colour is it?

Answer 22

Pale olive-green

Silicate mineral

Question 23

What kind of mineral is pyroxene and what colour is it?

Answer 23

Dark colour (black)
silicate

Question 24

What kind of mineral is amphibole and what colour is it?

Answer 24

Dark colours (various) 
silicate

Question 25

What kind of mineral is Mica?

Answer 25

Slicate It is various colours

Question 26

What kind of mineral is Feldspar and what colour is it?

Answer 26

Pink/ white/ colourless | Silicate

Question 27

What kind of mineral and what colour is silica?

Answer 27

Colourless | silicate

Question 28

What is the mean feature of the mica group?

Answer 28

Readily splits into thin flakes | Transparent in a single sheet

Question 29

Why does the mica group split into thin flakes?

Answer 29

it has cleavage perfectly parallel to the basal plane

Question 30

What are two common micas?

Answer 30

Muscovite (colourless/ silvery) | Biotite (dark brown to black)

Question 31

What happens when mica weathers?

Answer 31

Metal ions are removed from the minerals Results in soluble metal ions and clay minerals

Question 32

What are 2 common Feldspars?

Answer 32

``` Alkali Feldspar (pink or white) Plagioclase feldspar (white, colourless or grey) ```

Question 33

What reaction occurs when feldspar weathers?

Answer 33

Hydrolysis - a reaction between the minerals of water and the H+ and OH- ions present in water Ksilica +(H+OH-) --> HSilicate + (K+OH-)

Question 34

What is formed during the weathering of feldspar?

Answer 34

Kaolinite

Question 35

Where do extrusive igeneos rocks come from?

Answer 35

erupting volcanoes | oozing fissures

Question 36

How are extrusive igneous rocks formed?

Answer 36

When magma exits and cools above the Earth's surface

Question 37

Where do intrusive igneous rocks come from?

Answer 37

The Earth's crust, only visible after the higher levels of rocks are eroded away

Question 38

WHow are intrusive igneous rocks formed?

Answer 38

From molten rock insed the earth, cool at the earths crust

Question 39

What is the range of silica content in igneous rock?

Answer 39

From 40-80%

Question 40

How much silica does a felsic rock have?

Answer 40

high amounts

Question 41

How much silica does a mafic rock have?

Answer 41

Low amounts

Question 42

What are the 2 main types of Extrusive igneous rocks?

Answer 42

Fissure eruptions | Central eruptions

Question 43

What are the characteristics of a fissure erupted igneous rock?

Answer 43

Low viscosity, far flowing basaltic lava Produces fine-grained igneous rocks like plateau-basalt

Question 44

What are the defining characteristics of a central eruption?

Answer 44

Ejection of lava, gases and broken rock

Question 45

What is an example of a central erupted igneous rock?

Answer 45

Tuff - can be called a pyroclastic igneous rock

Question 46

What texture does an intrusive igneous rock have?

Answer 46

Equigranular

Question 47

What texture does and extrusive igneous rock have?

Answer 47

Aphantic texture

Question 48

What word describes chrystal of all the same size?

Answer 48

Equigranular

Question 49

What word describes crystals that are clearly larger than others?

Answer 49

inequigranular

Question 50

What word describes large crystals surrounded by much smaller crystals?

Answer 50

Porphyritic

Question 51

What facilitates the growth of larger and larger minerals?

Answer 51

The right temperature and pressure conditions for its continued growth

Question 52

Which word describes a crystal with a regular shape?

Answer 52

Euhedral

Question 53

What allows Euhedrals to form their natural shape?

Answer 53

They have had the space to grow Anhedral minerals grow to fit in a space Euhedral minerals form before Anhedral minerals

Question 54

What temperature do olivine and quartz chrystallise at?

Answer 54

Olivine: 1200 C Quartz: 700 C

Question 55

How does susceptibility to chemical weathering relate to the melting point they chrystallise at?

Answer 55

The higher the chrystallisation temperature, the more suscpetible to chemical weathering

Question 56

What kind of rocks are produced by the surface processes of the rock cycle?

Answer 56

Sedimentary

Question 57

What are the 2 types of sedimentary rocks?

Answer 57

- Clastic "standard" (exogenic) | - Non-clastic "others" (endogenic)

Question 58

What kind of sedimentary rocks have been deposited and either bedified or stratified horizontally?

Answer 58

Clastic

Question 59

What are the very important conditions in which sedimentary rocks are formed?

Answer 59

Depositional environment | The available settlements

Question 60

What sedimentary rock does mud turn into with pressure and temperature?

Answer 60

Shale

Question 61

What sedimentary rocks does sand with pressure and temperature turn into?

Answer 61

Sandstone

Question 62

What sedimentary rocks does gravel with pressure and temperature turn into?

Answer 62

Conglomerate

Question 63

What is the definition of shale?

Answer 63

Rocks formed from compact muds, finely laminated structure with a tendency to break along parallel side fragments. Mudstones typically break into blocky pieces

Question 64

What is an example of a non-clastic sedimentary rock?

Answer 64

Limestone (carbonate rock) | Evaporties (salt rocks)