Geology Q&A

Institute of Technology of Cambodia Geology: Prof, ENG Chandoeun
2018-2019 Prepared by: KEO Sokheng
Geology
Lesson 1
1. What is geology?
 Geology is the term derived from the Greek word which GEO mean Earth and LOGOS mean Science. It
is the study of the Earth, including the materials that it is made of, the physical and chemical changes that
occur on its surface and in its interior, and history of the planet and its life forms.
2. What civil engineer define geology?
 In civil engineering, geology provides necessary information about the site of construction phase
of an engineering project.
3. The relationship between Geological Engineering and other engineering sciences:
 Geological engineering helps
 Civil Engineering to study about Roads, Foundations, Tunnels, Slopes and Dams.
 Mining Engineering to study about Potash, Gold, Uranium and Coal.
 Petroleum Engineering to study about Oil, Natural Gas, Tar Sands and Oil Shale.
 Environmental Engineering to study about Groundwater, Wastes, Contaminations,
Pollution and Remediation.
4. What is the scope of geology engineering on civil engineer?
 The scope of engineering geology is best studied with reference to major activities of profession
of civil engineer which are: Construction, water resource development, town and regional
planning.
5. Why should study geology?
 Geology plays a very important role in the field of civil engineering such as:
 Planning:
 Topographic map
 Hydrological map
 Geological map
 Designing:
 Presence hard rock, their depth, and inclination with surface
 Mechanical properties of rock
 Presence of structural weakness
 Position of ground water and seismic nature of the area
 Construction:
Lesson 2
1. What is mineral?
 A mineral is a naturally occurring, solid crystalline substance, generally inorganic, with specific
chemical composition. Minerals are “building block” of rocks
2. What defines a mineral?
 Naturally occurring
 Inorganic
 Solid
 Specific composition (e.g., Gold-Au, Salt-NaCl, Quartz- SiO2)
3. How do we identification minerals?
 Chemical composition (microprobes and wet chemical methods)
 Crystal structure (X-ray diffraction)
 Physical properties (hardness, cleavage, fracture, color, specific gravity crystal habit)
4. What is cleavage?

 Cleavage: tendency of minerals to break along flat planar surfaces into geometries that are
determined by their crystal structure.
5. How do we classification the minerals?
 Silicate minerals:
 Silicate
 Ferromagnesian silicates
 Non- Silicate minerals
6. What are silicate minerals?
 Most important mineral group
 Made with silica tetrahedrons (light colored)
 Comprise most of the rock-forming mineral
 Very abundant due to large amounts of silicon and oxygen in Earth’s crust
7. Give example of silicate minerals?
 Feldspar
 Mica
 Olivine
 Quartz
 Pyroxene
8. What are Ferromagnesian Silicate Minerals?
 It is the combination of Silicate with iron and magnesium (darker)
9. Example of Ferromagnesian Silicate Minerals?
 Amphiboles
 Pyroxenes
 Olivine
 Garnets
 Kaolinite
10. How many groups of important non-silicate minerals?
 Oxides (Spinel, Hematite)
 Sulfides (Pyrite, Galena)
 Native Elements
 Carbonates (Calcite)
 Halides (Halite)
 Phosphates
11. What are the most common 6 minerals?
 The six minerals olivine, quartz, feldspar, mica, pyroxene and amphibole are the commonest
rock-forming minerals and are used as important tools in classifying rocks, particularly igneous
rocks.
12. How are minerals formed? Explain.
 Solution: if a solution is supersaturated, minerals will precipitate.
 Magma: minerals form during cooling of a magma – the slower a magma cools, the larger the
crystals.
 Metamorphism: transformation due to changes in pressure and temperature
13. What are magma and lava?
 Magma & Lava are the mixture of molten rock, gases and mineral phases, produced by mantle
melting.
14. What are rocks?
 An aggregate of one or more minerals; or a body of undifferentiated mineral matter (e.g.,
obsidian); or of solid organic matter (e.g., coal).

15. What is the classification of rocks?
 Igneous rocks (form by solidification of molten rock (magma))
 Sedimentary rocks (form by lithification of sediment 9sand, silt, clay, shells))
 Metamorphic rocks (form by transformations of preexisting rocks (in the solid state))
16. Describe the cycle of rocks?
 Magma
 Crystallization (freezing of rock)
 Igneous rocks
 Erosion
 Sedimentation
 Sediments & sedimentary rocks
 Tectonic burial and metamorphism
 Metamorphic rocks
 Melting
17. How many types of Igneous Rock?
 There are two: Intrusive and Extrusive.
 Intrusive (plutonic rock):
 Form within the Earth
 Slow cooling
 Interlocking large crystals
 Ex: Granite
 Extrusive (volcanic rock)
 Form on the surface of the Earth as a result of volcanic eruption
 Rapid cooling
 Glassy and/or fine-grained Texture
 Ex: basal
18. Example of igneous rocks:
 Andesite, Diorite, Gabbro, Tuff, Pumice and Obsidian
19. What is Sedimentary Rock?
 Sedimentary rocks are formed by from consolidation of sediments that are transported by water,
wind or ice, or deposited by organism.
20. The Formation of Sedimentary Rock:
 Weathering is breaking down of rock into sediments
 Erosion involves weathering and the transportation of sediments.
 Deposition is the process when water, wind, ice or gravity loses energy causing sediments to
drop
 Larger sediments are sediments are deposited first; smaller sediments are dropped later.
21. Kinds of Sedimentary Rocks:
 Sedimentary rocks can be placed into 3 groups on the basis of composition and origin: Siliclatic,
Chemical/Biochemical, and Carbonaceous.
22. What is silicate rock?
 Siliclastic rocks are composed dominantly of silicate minerals (quartz, feldspar, rock fragments).
These minerals originate mainly by chemical and physical breakdown (weathering) of igneous,
metamorphic, older sedimentary rock. Ex: sandstone and shales, volcanicclastic.
23. What is Chemical/Biochemical sedimentary rock?
 Chemical/Biochemical sedimentary rocks are composed of minerals precipitated mainly from
ocean or lake water by inorganic (chemical) and/or organic (biogenic) processes. Ex: limestone,
chert, evaporates (gypsum, phosphorites, iron-rich sedimentary rocks.

24. What is Carbonaceous rock?
 Carbonaceous rocks contain a substantial amount (>~15%) of highly altered remains of the soft
tissue of plants and animals, referred to as organic matter. Ex: coal, oil shale.
25. What is Metamorphic Rock?
 The rocks which have formed through the operation of various types of metamorphic processes
on the pre-existing igneous and sedimentary rocks involving changes in textures, structures and
mineralogical compositions.
26. What is the formation of metamorphic rock?
 Form by heat and pressure changing one type of rock into another type of rock.
 Form near intrusions, at plate subduction zones and in deep mountain root.
Lesson 4
1. What are superficial deposits?
 Superficial deposits refer to the most recent geological deposits, unconsolidated sediments,
including stream channel and floodplain deposits, beach sands, talus gravels and glacial drift and
moraine.
2. What is Soil?
 Geologists use the term to refer to any rock waste, produced by the disintegration of rocks at the
surface by weathering processes, which has formed in situ.
 Engineers use the term to refer to any superficial or surficial deposit which can excavated
without blasting.
3. What are the parents of rocks?
 Parent Rock are Igneous, Sedimentary, Metamorphic.
4. What is Residual soil?
 In situ weathering (by physical &chemical agents) of parent rock.
 Transported soil (weathered and transported far away and Transported by: wind, water, ice).
5. How do we classify the soil?
 By their liquid limit and Plastic limit.
 The liquid limit is arbitrarily defined as the water content, at which a pat of soil in
standard cup and cut by a groove of standard dimensions (13 mm) will flow together.
 Plastic limit is water content at which a soil can no longer be deformed by rolling into 3.2
mm diameter threads without crumbing.
6. What is Atterberg Limit?
 It is used to determine the plastic and liquid limits of a fine-grained soil.
7. What is Coarse Soil?
 The microstructure of sand and gravel refers to its particle arrangement that, in turn, involves its
packing.
 Grain size and sorting have a significant influence on the engineering behavior of coarse soil.
 Larger particles, the higher the strength, and deposits consisting of a mixture of different-sized
particles usually are stronger than those that are uniformly graded.
 Ex: sand-gravel mixture has a significant effect on shear strength.
8. What is silt and loess?
 Silt is granular material of a size between sand and clay, whose mineral origin is quartz and
feldspar. It occurs as a soil (sand mixed with clay) or sediment mixed in suspension with water
and soil in a body of water, e.g. river.
 Loess: wind-blown deposit comprised predominantly of silt-size particles (20 -60 µm).
9. What is the Clay deposit?

 Clay deposits are composed principally of fine quartz and clay minerals (kaolinite, illite and
montmorillonite).
10. What cause the settlement of building?
 Clays shrink where they dry out, causing settlement of building.
11. How Ferruginous and aAluminous clay product?
 Ferruginous and aluminous clay soils are frequent products of weathering in tropical latitude.
They contain iron and aluminum oxides and hydroxides.
12. What is Dispersive Soil also called Sodic Soils?
 It is the soil that are:
 dislodged easily and rapidly in flowing water.
 Highly susceptible to erosion and containing high percentage of exchangeable sodium
ions.
 Disperse into basic particles (sand, silt and clay), even in still water.
13. What are the Problems caused by dispersive soils?
 Surface erosion
 Tunnel formation
 Gully formation
 Sinkholes
 High suspended sediment loads
14. The Frost action in soil:
 Sever damages to pavement layers may result from frost action.
 Due to freezing soil volume increase and cause ice crystals and lenses
 Frost Heave: distortion or expansion of the subgrade soil or base during freezing temperature.
 During spring ice lenses melt which result in water content increase => reducing strength of the
soil
15. The Occurrence require to Frost action in soil:
 shallow water table that provide capillary to frost line
 frost susceptible soil (most server in silty soil)
 ambient temperature must be lower than zero for several days
16. The Treatment to Frost action in soil:
 remove soil subjected to frost action
 replace with suitable granular backfill to the depth pf frost line
 installation of drainage facilities to lower water table
 restricting truck traffic during spring
17. What is the Organic soil?
 Large amount of organic matter
 Dark brown to black color and distinctive odor.
 Soft, wet, unconsolidated
 It can give rise to geotechnical problems in area of sampling, settlement, stability…
Lesson 4
1. Planning is to determine a particular course of action.
2. What is geological information?
 Geological information is required at all levels of planning and development from the initial
identification of a social need to the construction stage.
3. Why geological information is necessary after construction?
 After construction, geological information is necessary in the form of advice on hazard
monitoring, maintenance or remedial works.

4. What is Geological hazard?
 Geological hazard is an extreme natural event in the crust of the earth that pose a threat to life,
structure, and other property. crust of the earth that pose a threat to life, structure, and other
property.
5. What are the Natural geohazard includes?
 Volcanic activity
 Earthquake
 Landslides and slope movement
 River action and flooding
 Marine action
 Wind action
 Glacial hazard
6. What Geological Hazards, Risk Assessment and Planning included?
 It includes:
 Waste disposal
 Subsidence due to mining
 Subsidence due to the abstraction of fluid
 Induced sinkholes
 Induced seismicity
7. Development of planning policies for dealing with geohazards:
 Evaluation the degree of risk (life, property, possessions and environment)
 Vulnerability analysis (classification of risk and geohazard)
 Prevention and mitigation measures (structural and technological)
The information related to this problem can be mapped as Hazard Map.
8. What is hazard map?
 Hazard map provides idea of the engineering problems that may arise in the area. It should be
provided information relating to the special and temporal probabilities of the hazard. Included:
 Any special aspect of hazard
 Data from surveys (history of past and future hazard of study area)
 Degree of hazard
 Specific risk zoning or zones indicating exposure to a specific hazard
9. What is Volcanic activity?
 Volcanic activity referred to Volcanic eruption is a process wherein volcanic materials such as
molten or hot fragmented rocks, or gaseous materials are ejected from a volcano.
10. What are the Geohazard includes?
 Geohazard includes:
 Lava flow
 Lahar flow (mudflows)
 Flood (sudden melting of snow and ice)
 Tsunamis generated by explosive eruption
 Poisonous gases
11. What are the Prevention and Mitigation of volcanic eruption?
 Losses caused by volcanic eruptions can be reduced by combination of prediction, preparedness
and land-use control. Example:
 Building steeply pitched reinforced roofs that are unlikely to be damaged by ash fall.
 Constructing walls and channels to deflect lava flows
 Forecasting eruption

12. What is an earthquake? And its Geohazard includes.
 An earthquake is a shaking of the ground caused by sudden slippage of rock masses below or at
the surface of the earth. Geohazard includes:
 landslides, floods, subsidence, tsunamis
13. What are the Prevention and Mitigation to seismic?
 Seismic evidence obtained from history record
 Estimates strong ground motion
 Identifies seismic or micro-seismic zoning
 Seismic monitoring
 Earthquake resistance design
14. What is the Landslide and slope movements?
 Massive outward and downward movement of slope-forming materials
 The term landslide is restricted to movements of rocks and soil masses
 Initiated when a section of a hill slope is rendered too weak to support its own weight
15. What are the Prevention and Mitigation to Landslide and slope movements?
 Collect data from landslide hazard map (Why, When, where landslides are likely to occur)
 Geomorphological mapping, aerial photograph, satellite image
 Subsurface investigation, sampling, pore water pressure testing.
 Removing unstable materials from the slope
 Slope reduction (stabilize the toes of slope, benching of steeper slope)
 Slope flattening
 Drainage
 Restraining structures control landslides (retaining walls, rock anchors...)
16. What is the River action and flooding?
 All rivers form part of a drainage system, the form of which is influenced by rock type and
structure, the nature of the vegetation cover and climate.
17. What is Flood?
 Floods represent one of the commonest types of geological hazard. However, flooding is more
predicable than earthquake and landslide.
18. What are the Prevention and Mitigation of River action and flooding?
 Identifies flood zones from historical evidence (magnitude of floods, amount of damage…)
 determines the discharge rate, size and depth of area of inundation, and duration of flood.
 designs the flood plains for specific types of land-use:
 Channel zone: water should be flowed freely without obstruction
 Bridges: should allow sufficient waterway capacity
 Area with recurrence interval of 1 -20 years: should be used for agriculture
 Area with recurrence interval of 20 -100 years: uses for building construction
19. What is the marine action?
 Waves, acting on beach materials, are a varying force. They vary with time and place due to:
 Changes in wind force and direction
 Changes in costal aspects and offshore relief
20. What is the Problem cause by marine action?
 Coastal erosion
 Cliff land sliding
 Submarine slope becomes very wide

21. What are the Prevention and Mitigation to marine action?
 Investigation the landforms and rock formations along the beach and adjacent rivers, giving
particular attention to their durability and stability.
 Seismicity study
 Estimates the rate of erosion
 Topography and hydrology surveys
 The groyne construction
 Storm tide warning services
 Tsunamis monitoring (e.g., seismograph…)
 Building can be constructed with reinforced concrete frames and elevated on reinforced concrete
piles with open spaces at ground level (e.g., for parking, tsunamis may flow through the
ground...)
22. What is the Wind action?
 In arid regions, because there is little vegetation and the ground surface may be dry, wind action
is much more significant, and sediment yield may be high.
 There is high soil erosion
 Migration of sand dunes (sand and dust storm)
 Movement of sand can bury obstacles in its path such as roads, railway or accumulate against
large structures.
23. What are the Prevention and Mitigation of wind action?
 Meteorological data analysis (structures may be pitted or fluted relates to wind direction)
 Areal photos and remote sensing imagery (study dune movement)
 Removing sand at construction site (depend on quantities of sand)
 Stabilizes mobile sand (vegetative cover, natural geotextiles, chemical spray…)
 Gravel or coarse aggregate can be placed over a sand surface to prevent its deflation
24. What is the Glacial hazard?
 The rapid movement of masses of snow or ice down slopes as avalanches can pose a serious
hazard in many mountain areas.
 Glacier flood
25. What is Waste disposal?
 Mining waste, domestic waste, commercial waste, industrial waste…
 Deposited wastes can undergo changes through chemical reactions, resulting in dangerous
substances being developed.
26. What are the Waste disposal treatment and management?
 Site exploration to determine the geological and hydrological conditions
 Chemical analysis of groundwater
 Mineralogical analysis of soil and rock
 Making impermeable layer (clay, cement or plastic lining...)
 Dilution and dispersion of leachate
 Selection landfill site for a particular waste or a mixture waste
 Properly designed and constructed new site for long-term protection of ground and surface water
27. What is the Subsidence due to mining?
 The subsidence effects of mineral extraction are governed
 Consideration mining methods and properly mining design for each mineral deposit
 Geological condition (fault, rock types, stress...)
 Hazard maps recorded safe and unsafe mining zones
 Consideration shape, size, and form of building before construction at mining area

28. What is the Subsidence due to the abstraction of fluid?
 Subsidence due to the withdrawal of groundwater has developed with most effect in those
groundwater basins where is intensive abstraction because the total overburden pressure in
saturated deposits is borne by their granular structure and pore water.
 Investigation rate subsidence during groundwater extraction (e.g., few centimeters per year)
 Investigation fault or fissure on the surface
 Injection water for oil and gas extraction
29. What is the Induced Sinkhole?
 Many sinkholes are induced by man’s activities, that is, they result from declines in groundwater
level, especially those due to excessive abstraction.
 Most collapses forming sinkhole result from roof failures of cavities in unconsolidated deposits
30. What is the Induced Seismicity?
 Induce seismicity occurs where changes in the local stress conditions brought about by man give
rise to changes in strain and deformation in rock masses. Ex: hydrocarbon exploitation
 Earthquake can generate with less or more than 5 of magnitude

Geology Q&A

More Related Content

What's hot (20)

Similar to Geology Q&A (20)

More from KeoSokheng (6)

Recently uploaded (20)

Geology Q&A