(MODULE 8) INTRODUCTION TO ENGINEERING GEOLOGY, GEOLOGIC STRUCTURES, AND GEOLOGIC MAPS

Question 1

the science of rocks, minerals, soils, and surface water, including the study of their formation, structure, and behavior

Answer 1

geology

Question 2

the branch of geology that deals with the application of geologic principles to engineering works

Answer 2

engineering geology

Question 3

the work of this type of geologist includes mapping, describing and characterizing the rock at a construction site; assessing stability issues, such as landslides; and appraising local seismicity and earthquake potentials

Answer 3

engineering geologist

Question 4

the branch of civil engineering that deals with soil, rock, and underground water, and their relation to the design, construction, and operation of engineering projects

Answer 4

geotechnical engineering

Question 5

what are the phases of geotechnical engineers’ methodology?
1.
2.
3.

Answer 5

1. design phase
2. construction phase
3. beyond the construction phase

Question 6

for the design phase, geotechnical engineers begin by assessing the underground conditions and the engineering properties of the various strata. we call this process ___.

Answer 6

site exploration and characterization

Question 7

what are the two steps of the design phase done by geotechnical engineers?

Answer 7

1. geotechnical engineers begin by assessing the underground conditions and engineering properties of the various strata through site exploration and characterization.
2. the next step is to perform engineering analyses based on the information gained from the first step, through tools known as soil mechanics and rock mechanics

Question 8

the analytical tools used for doing the second step of the design phase are ___ and __.

Answer 8

soil mechanics and rock mechanics

Question 9

the construction phase involves three steps:
1.
2.
3.

Answer 9

1. examining the soil and rock conditions actually encountered and comparing that to what is anticipated in the design
2. comparing the performance between the two
3. providing quality control testing, especially in compacted fills and structural foundations

Question 10

beyond the end of construction, two steps are followed:
1.
2.

Answer 10

1. monitoring of long-term settlements
2. development of remedial measures to address geotechnical problems

Question 11

what are the differences between rock and soil?
1.
2.
3.
4.
5.

Answer 11

1. rocks are generally cemented whereas soils are rarely cemented
2. rocks usually have less pores than soils
3. the effects of weathering on soils are more subtle and less variable than on rocks
4. rocks are often discontinuous due to the presence of fractures whereas soil masses can be represented as continuous
5. it is harder to identify the stress histories of rocks

Question 12

the study of the configuration and orientation of rock formations

Answer 12

structural geology

Question 13

structural geology is an important part of engineering geology because ___.

Answer 13

it gives us important insights on how a rock mass will behave

Question 14

dynamically-produced patterns or arrangements of rock or sediment from, and give information about, forces within the earth

Answer 14

geologic structures

Question 15

force per unit area

Answer 15

stress

Question 16

the three basic types of stress are
1.
2.
3.

Answer 16

1. compressive
2. tensional, and
3. shear

Question 17

a change in size or shape, or both in response to stress

Answer 17

strain

Question 18

geological structures are indicative of
1.
2.
3.

Answer 18

1. the type of stress
2. the rate of application of such stress
3. physical properties of the rocks or sediments

Question 19

this type of stress results in rocks being shortened or flattened

Answer 19

compressive stress

Question 20

rocks that have undergone compressive stress are found along ___.

Answer 20

convergent plate boundaries

Question 21

this type of stress results in a stretching or extension and breaking of material

Answer 21

tensional stress

Question 22

rocks that have undergone tensional stress are found along ___.

Answer 22

divergent plate boundaries

Question 23

because rocks are weak when pulled apart, ___ and ___ are common structures.

Answer 23

fractures and faults

Question 24

when stresses act parallel to a plane, ___ is produced.

Answer 24

shear stress

Question 25

a shear stress results in a ___ parallel to the direction of the stresses.

Answer 25

shear strain

Question 26

how do rocks respond to stress?

Answer 26

rocks remain elastic (bounce back to its original form) at low pressures, but deforms permanently when exceeding its elastic limit. ductile rocks deform through bending plastically whereas brittle rocks deform through fracturing.

Question 27

rocks exposed to elevated pressure and temperature behave in a ___ manner, and undergo foliation.

Answer 27

ductile

Question 28

ductile behavior results in rocks permanently deformed by ___.

Answer 28

folding or bending of rock layers

Question 29

rocks exhibit ___ at or near earth's surface, where temperatures and pressure are low.

Answer 29

brittle behavior

Question 30

bends or wavelike features in layered rock

Answer 30

folds

Question 31

the ___ divides a fold into two limbs.

Answer 31

axial plane

Question 32

the subtle trace of an axial plane is called the ___ of the fold.

Answer 32

hinge line

Question 33

upward-arching folds with the oldest rocks in the center of the fold

Answer 33

anticlines

Question 34

downward-arching folds with the youngest rocks in the center of the fold

Answer 34

synclines

Question 35

types of folds 1. 2. 3. 4. 5. 6. 7.

Answer 35

1. plunging folds 2. open folds 3. isoclinal folds 4. overturned folds 5. recumbent folds 6. structural domes 7. structural basins

Question 36

folds in which the hinge line is not horizontal

Answer 36

plunging folds

Question 37

folds which have limbs that dip gently and the angle between the limbs is large

Answer 37

open folds

Question 38

the more open the fold, the ___ it has been strained by shortening.

Answer 38

less

Question 39

open folds are exposed to ___ stress levels.

Answer 39

lesser

Question 40

folds which have parallel limbs; implies even larger shortening strain or shear strain; forms a hairpin shape

Answer 40

isoclinal folds

Question 41

folds wherein the axial plane is inclined to an extent where fold limbs dip diagonally and parallel to each other

Answer 41

overturned fold

Question 42

folds overturned to the point where the limbs are horizontal

Answer 42

recumbent folds

Question 43

structures in which the beds dip away from a central point, with the oldest rocks lying at the center of the structure

Answer 43

structural domes

Question 44

structural domes are also called ___.

Answer 44

doubly plunging anticlines

Question 45

structures in which the bends dip toward the central points, with the youngest rocks lying at the center of the structure

Answer 45

structural basins

Question 46

structural basins are also called ___.

Answer 46

doubly plunging anticlines

Question 47

a fracture or crack in bedrock where essentially no displacement occurs

Answer 47

joint

Question 48

where joints are oriented approximately parallel to one another

Answer 48

joint set

Question 49

when counting joint sets, you could the count the number of ___ on the rock.

Answer 49

orientations

Question 50

When we say fractures in rock, they are the sources of discontinuities, and that they have ___.

Answer 50

impurities

Question 51

How do discontinuities contribute to mass wasting?

Answer 51

discontinuities can weaken when the fractures become looser, causing mass wasting.

Question 52

fractures in bedrock along which movement has occured

Answer 52

faults

Question 53

faults are considered ___ if movement has occurred along them within the last 11,000 years

Answer 53

active

Question 54

types of faults 1. 2. 3.

Answer 54

1. dip-slip faults 2. strike-slip faults 3. oblique-slip faults

Question 55

faults wherein the movement is up or down parallel to the dip of the inclined fault surface

Answer 55

dip-slip faults

Question 56

parts of dip-slip faults: the side of the fault above the inclined fault surface is called the ___

Answer 56

hanging wall

Question 57

parts of dip-slip faults: the side below the fault is called the ___

Answer 57

footwall

Question 58

types of dip-slip faults 1. 2. 3.

Answer 58

1. normal faults 2. reverse faults 3. thrust fault

Question 59

a ___ results in extension or lengthening of the crust

Answer 59

normal fault

Question 60

fault blocks, bounded by normal faults, that drop down

Answer 60

graben

Question 61

fault blocks, bounded by normal faults, that are uplifted

Answer 61

horsts

Question 62

horizontal compressive stresses cause ___ which tend to shorten the crust.

Answer 62

reverse faults

Question 63

a reverse fault in which the dip of the fault of the plane is at a low angle (30°) or even horizontal

Answer 63

thrust fault

Question 64

faults which have movement that is horizontal and parallel to the strike of the fault plane

Answer 64

strike-slip faults

Question 65

faults which have movement with both vertical and horizontal components

Answer 65

oblique-slip faults

Question 66

a ___ shows the distribution of geologic features, including different kinds of rocks and faults

Answer 66

geologic map

Question 67

the geology is represented by ___, ___, and ___ unique to geologic maps

Answer 67

colors, lines, and special symbols

Question 68

geologic units are named and defined by the ___

Answer 68

geologists who made the geologic map

Question 69

the most common division of time used is the period, represented through ___.

Answer 69

letter symbols

Question 70

geologic period of 195 to 141 million years ago

Answer 70

jurassic

Question 71

geologic period of 141 to 65 million years ago

Answer 71

cretaceous

Question 72

geologic period of 65 to 2 million years ago

Answer 72

tertiary

Question 73

geologic period of 2 million years ago to today

Answer 73

quartenary

Question 74

letter symbols for 1. jurassic 2. cretaceous 3. tertiary 4. quaternary

Answer 74

1. J 2. K 3. T 4. Q

Question 75

the place where two different geologic units are found next to each other is called a ___.

Answer 75

contact

Question 76

contacts are represented in a geologic map through different kinds of ___

Answer 76

contact lines

Question 77

the two main types of contacts shown on most geologic maps are ___ and ___.

Answer 77

depositional contacts and faults

Question 78

lava from a volcano flows over the landscape. when the lava hardens into rock, the place where the lava-rock rests on the rocks underneath is a ___.

Answer 78

depositional contact

Question 79

what is a depositional contact

Answer 79

the place where the hardening lava-rock rests on the rocks underneath

Question 80

depositional contacts is shown on the geologic map as a ___

Answer 80

thin line

Question 81

when different geologic units have been moved next to one another after they were formed, the contact is a ___.

Answer 81

fault contact

Question 82

what is a fault contact?

Answer 82

a fault contact is when different geologic units move next to one another

Question 83

fault contacts are shown on the map by a ___

Answer 83

thick line

Question 84

geologic units can also be bent and warped by the same forces into rounded, wavelike shapes called ___

Answer 84

folds

Question 85

a line that follows the crest or trough of the fold is called the ___.

Answer 85

fold axis

Question 86

this is marked on a geologic map with a ___

Answer 86

line thicker than a depositional contact but thinner than a fault

Question 87

all thickness of lines are also modified by being ___, ___, or ___.

Answer 87

solid, dashed, or dotted

Question 88

the places where the line is precisely located are shown as ___

Answer 88

solid lines

Question 89

places where the line is uncertain in location are shown as ___

Answer 89

dashed lines

Question 90

the shorter the dash of a dashed line in a geologic map, ___

Answer 90

the more uncertain the location

Question 91

the compass direction of a line followed by the intersection of an inclined plane with a horizontal plane

Answer 91

strike

Question 92

the ___ shows that horizontal direction in the beds; the short line is called the ___ and shows which way the bed tilts; the number is called the ___ and shows how much the bed is tilted, in degrees, from flat.

Answer 92

1. strike line 2. dip line 3. dip