What does clastic texture refer to?
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Rocks made up of broken fragments of preexisting rocks and assorted minerals bound together by another mineral or chemical.
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What does clastic texture refer to?
Rocks made up of broken fragments of preexisting rocks and assorted minerals bound together by another mineral or chemical.
What are the three main types of rocks?
Igneous rocks, Sedimentary rocks, and Metamorphic rocks.
What is the difference between extrusive and intrusive igneous rocks?
Extrusive rocks form from lava that cools on the Earth's surface, while intrusive rocks form from magma that cools beneath the surface.
What is the basic unit discussed in Mitchell's 1993 summary?
The basic unit refers to fundamental concepts in engineering geology.
What are the final products of weathering?
Soils.
What are the three main forces interacting between clay particles?
Van der Waals attraction, double layer repulsion, and Coulombian attraction.
How are clastic sedimentary rocks formed?
By transportation, sedimentation, and chemical cementation, pressure, and/or temperature.
What is the main topic of the section titled 'III. Soil formations and deposits'?
Soil formations and deposits.
What minerals are primarily contained in igneous rocks?
Silicates.
Under what conditions may tectonic joints be formed?
Under shear or tension.
What is lava?
Molten rock from volcanoes deposited on the surface.
What is the effect of hydration energy on clay layers?
It causes the clay layers to expand due to repulsive forces.
What are the two main types of interactions between clay particles?
Interlayer and interparticle interactions.
What is a key characteristic of clay minerals?
They have a high surface area and can retain water.
What type of rock is igneous?
A type of rock formed from the cooling and solidification of magma or lava.
What is a characteristic of minerals higher in Bowen's Reaction Series?
They are more stable.
What are the three ingredients necessary for potentially damaging swelling in soil?
What is saprolite?
Rock fabric is retained.
What is residual soil?
Rock fabric is completely destroyed.
What is the effect of the strong attraction from the clay surface on water molecules?
It alters the properties of the water molecule 'locked' in the adsorbed layers compared to bulk water.
What is the typical surface area of Illite including the interlayer surface?
700 - 840 m²/gm.
How do the engineering properties of residual soils compare to transported soils?
They are different.
What is the AFCD Lions Nature Education Centre?
A facility focused on nature education and conservation.
What does DLVO stand for in the context of clay particle interactions?
Derjaguin-Landau-Verwey-Overbeek forces.
What is a common process involving feldspar in decomposed granite?
The alternation of feldspar into kaolinite.
What causes double layer repulsion in clay particles?
The overlapping of the double layer.
What are the two important physical processes of weathering?
Alternate wetting and drying, and exfoliation (sheeting).
What are plutonic rocks?
Volcanic rocks that are intruded into pre-existing materials below the Earth's surface.
What type of education does the AFCD Lions Nature Education Centre provide?
Nature education and conservation awareness.
What is osmotic pressure in the context of clay-water interaction?
The pressure resulting from the concentration difference of cations and water diffusion.
What are residual soils?
Soils that remain at the original place after weathering.
Why is understanding geology important for engineering?
To assess risks and ensure the stability of structures.
What are some common types of clay minerals?
Kaolinite, illite, and montmorillonite.
What are the basic components of clay in terms of structure?
Layers and particles.
What process causes hot water to rise and then cool?
Convection.
What types of deposits can form from animal shells?
Limestone or chert.
What does the distance in the diffuse double layer relate to?
Concentration and exponential decay.
What occurs when tectonic plates converge?
A cooled plate is dragged under, sinks, warms, and rises again.
What does the hydrogen ion do in the clay formation process?
It displaces cations from the feldspar.
What is the colloquial name given to rose-like formations of crystal clusters of gypsum or baryte?
Desert Rose.
What is the general charge of external or interlayer surfaces of clay particles?
Negatively charged.
Where are earthquakes most commonly found?
At plate boundaries.
What is a polar molecule?
A molecule with a partial positive charge on one side and a partial negative charge on the other, such as water.
What stability issues can arise from foliated and bedded rocks?
They can cause landslides and stability problems in excavations.
What is the main mineral of sand particles in general?
Quartz.
What is the main characteristic of noncrystalline clay?
It lacks a defined crystal structure.
What are tectonic joints associated with?
Regional tectonic deformation, typically with faults or pluton emplacement.
What does higher stability in Bowen's Reaction Series indicate?
Higher weathering resistance.
What is the focus of Basic Engineering Geology?
The study of geological factors that affect engineering projects.
Why do lava rocks generally contain small crystals?
Because of rapid cooling at the surface.
Why is a source of water important for potentially swelling clay?
It provides the necessary moisture for the swelling process.
How are residual soils formed in Hong Kong?
Due to the warm climate and abundant rainfall decomposing the top layer of rock.
What role does the Hong Kong Geological Survey play?
It provides geological information and assessments for engineering projects.
What role does carbon dioxide play in the formation of clay minerals?
CO2 dissolves in water to form carbonic acid, which makes water slightly acidic and reacts with rock surfaces.
What type of programs does the AFCD Lions Nature Education Centre offer?
Educational programs related to nature and wildlife conservation.
What do the terms dip and strike describe?
The spatial orientation of geologic features such as rock layers, joints, folds, and faults.
What is interstratification in the context of transported soils?
The layering of silts and clays.
What is a characteristic of water flow in tunnels?
Water flows easily into the tunnel.
What are examples of chemical sedimentary rocks?
Rock salts.
What is the basic unit of silicate minerals?
Silica tetrahedra.
What happens to brittle rocks when subjected to tectonic forces?
They may break along faults, generating an earthquake.
What do tectonic joints facilitate in the rockhead?
The infiltration of groundwater and the development of linear depressions.
What type of metamorphic rocks are Schist and Phyllite?
Foliated metamorphic rocks containing significant amounts of mica.
What happens to the minerals of the original rock during metamorphism?
They may be replaced by new metamorphic minerals, such as micas and amphibole.
What is the chemical reaction that leads to the formation of clay from feldspar?
Feldspar + hydrogen ions + water → clay (kaolinite) + cations + dissolved silica.
Does Kaolinite exhibit interlayer swelling?
No, there is no interlayer swelling.
What are common features studied in structural geology?
Folds, faults, and joints.
What does structural geology study?
The arrangement and relationship of rocks and geological structures.
Where can you find detailed maps and trails for hiking in Sai Kung?
Hong Kong Hiking Federation.
What are joints in geology?
Fractures or cracks in rocks along which there has been no detectable displacement.
What are the main layers of the Earth?
A dense molten core, a quasi-solid to ductile mantle, and a thin crust.
What is a key characteristic of residual soils?
They are typically heterogeneous and can vary significantly in composition.
What are clay minerals?
Minerals that form from the weathering of rocks and are important in soil composition.
What type of rocks often have planes of weakness that can lead to landslides?
Foliated and bedded rocks.
What is the nature of the net interparticle force in a flocculated fabric?
The net interparticle force is attractive.
How are igneous rocks formed?
From the solidification of molten magma or lava.
What is a normal fault?
A type of fault where the hanging wall moves down relative to the footwall.
What is a commonly occurring extrusive rock in Hong Kong?
Tuff.
What is an important aspect of modern geology and geophysics?
The study of plate tectonics.
What characterizes the tectonic plates in terms of their physical properties?
They are large, solid, and relatively brittle.
Where are metamorphic rocks generally formed?
Deep within the Earth or where tectonic plates meet.
Which minerals are classified as oxides?
Limonite and hematite.
What types of soluble rocks can lead to sinkholes?
Carbonates and gypsum.
What is the role of van der Waals attraction in clay particle interaction?
It contributes to the net force between clay particles.
What year was the summary by Mitchell published?
What is the geological map of Hong Kong used for?
To represent the geological features and formations of the region.
What are clay minerals primarily composed of?
Silicate minerals that are layered and fine-grained.
How many monolayers are mentioned in the context of clay surfaces?
3 monolayers.
What type of shape does Kaolinite have?
Platy shape.
What role do clay minerals play in engineering?
They can affect the stability and behavior of soil in construction projects.
What ions are produced when carbonic acid dissociates in water?
Hydrogen ions (H+) and bicarbonate ions (HCO3-).
What happens to feldspar when it reacts with acidic water?
It tends to dissolve potassium ions and silica, transforming into kaolinite.
What is the final product of the reaction between feldspar and acidic water?
Kaolinite.
What are the primary components of the Earth's crust?
Minerals and rocks.
What is the behavior of rocks at or near the Earth's surface?
They are hard and generally behave in a brittle manner.
How does water behave when it comes to exiting tunnels?
Water is easy to flow out from the tunnel.
What is a mineral?
A naturally occurring inorganic solid with a definite chemical composition and crystalline structure.
What is the primary cause of recorded seismic activity?
Plate intersections.
What is the chemical formula for Illite?
Si8(Al,Mg,Fe)4 ~ 6 O20(OH)4·(K,H2O)2.
Why are plate boundaries common sites for earthquakes?
Because the rocks in these locations are subject to the greatest tectonic forces.
What type of igneous rock is tuff classified as?
Extrusive or volcanic.
What is the origin of biological sediments and rocks?
They have an organic origin.
What is the chief constituent of many shales?
Illite.
What effect does metamorphism have on the original textures of rocks?
The original textures are commonly masked due to deformation such as shearing and folding.
What is the significance of the interaction between water and clay in engineering?
It affects the stability and behavior of soil in construction and geotechnical applications.
What does Irfan's 1999 study characterize?
Weathered Volcanic Rocks in Hong Kong.
What is the chemical formula for dolomite?
CaMg(CO3)2.
What colors can pure and impure marble be?
Pure marble is white or creamy; impure marble may be light grey to bluish grey.
What are the dominant minerals in soils formed from the weathering of granitic rocks?
Kaolinite, quartz, halloysite, and occasional K-feldspar.
What causes charge deficiencies in clay particles?
Isomorphous substitution of silicon and aluminum by other cations.
What is pyrite commonly known as?
Fool's gold.
What website provides information on different types of rocks?
What type of forces bond the interlayers in Montmorillonite?
Van der Waals forces and cations.
How does joint spacing in coarse-grained rocks compare to fine-grained rocks?
Wider in coarse-grained rocks, such as granite, than in fine-grained rocks, such as tuff.
What are micas composed of?
Potassium, magnesium, iron, aluminium, silicon, and water.
What is an example of noncrystalline clay mentioned?
Allophane.
What are the categories of decomposition for residual soils mentioned?
Completely decomposed, highly decomposed, moderately decomposed, slightly decomposed, and fresh.
Where are clay minerals commonly found in rock masses?
In the filling materials of joints and faults (fault gouge, seam).
What type of clay is specifically mentioned as a factor in swelling potential?
Montmorillonite.
What is the crystal radius of Na+?
0.095 nm.
What is the chemical formula for Kaolinite?
Si4Al4O10(OH)8.
What is the basal spacing of Kaolinite?
7.2 Å.
What defines the foliation in metamorphic rocks?
The alignment of platy or elongate prismatic minerals.
Why is structural geology important in engineering?
It helps in understanding the stability of geological formations for construction projects.
What are the main components of the Earth's structure?
Minerals and rocks.
What happens to rocks at high temperatures and pressures deep in the Earth's crust?
They become pliable and behave in a plastic or ductile manner.
How does structural geology relate to tectonics?
It examines how tectonic forces shape the Earth's crust.
What is the primary goal of the AFCD Lions Nature Education Centre?
To promote awareness and understanding of nature and conservation.
What happens to shales when exposed to water or air?
They can swell or soften, becoming weak and compressible.
What features are influenced by the jointing pattern in rocks?
Cliff faces, tors, and boulders.
How do joints affect the strength and permeability of rock mass?
Joints usually make a rock mass weaker and more permeable.
What defines a recumbent anticline?
An anticline that has been folded over so that its axial plane is nearly horizontal.
What is the lithosphere composed of?
The crust and the outermost part of the mantle.
What is the basic shape of Illite?
Flaky shape.
What is the structure of a water molecule?
It consists of two hydrogen atoms (H+) and one oxygen atom (O-).
What are lithospheric plates?
Large sections of the Earth's crust that move and interact with each other.
Which publication provides a guide to rock and soil description?
Guide to Rock and Soil Description (1988).
What is the size range of columnar joints in the High Island Formation?
Up to 1.2 m in diameter and up to 30 m tall.
What minerals are included in the carbonate group?
Calcite and dolomite.
What engineering problems can arise when constructing dams on soluble rocks?
Dams can fail and reservoirs can leak.
What are some common uses of slate?
Roofing, flooring, and flagging.
What is a distinctive feature of sedimentary rocks?
They commonly have distinctive layering or bedding.
What can chemically aggressive groundwater cause in soluble rock areas?
It can lead to sinkholes.
What does 'laminated' mean in the context of shale?
The rock is made up of many thin layers.
Can you name examples of foliated metamorphic rocks?
Slate, schist, and gneiss.
What is the range of basal spacing in Montmorillonite after swelling?
From 9.6 Å to ¥.
What type of rocks do most residual soils in Hong Kong decompose from?
Igneous rocks.
What are volcanoclastics?
Clastic rocks of volcanic origin.
What is the concentration of cations in the interlayers compared to the solution?
Higher in the interlayers due to negatively charged surfaces.
What happens to water molecules when added to clay?
They wedge into the interlayer.
What is Coulombian attraction in the context of clay particles?
Attraction between the positive edge and negative face of clay particles.
How do the surfaces of shear joints differ from tension joints?
Shear joints have smooth surfaces, while tension joints have relatively rough surfaces.
What is a notable characteristic of tectonic joints in Hong Kong?
They are generally very persistent.
Why are plutonic rocks coarsely crystalline?
Because they have cooled very slowly at depth, allowing larger mineral crystals to form.
What is the main goal of the AFCD Lions Nature Education Centre?
To promote understanding and appreciation of nature.
What is the origin of clay minerals?
The contact of rocks and water produces clays, either at or near the surface of the earth.
What types of bonding exist between layers of Kaolinite?
Van der Waals forces and hydrogen bonds.
What can accumulations of carbon-rich plant material form?
Coal.
What is the charge of the surface of a clay particle in the diffuse double layer?
Negatively charged.
What is a common problem related to dams?
Leakage problems.
What do plastic rocks form when subjected to tectonic forces?
Folds.
How are colluvial soils described in terms of consolidation?
They are usually poorly consolidated.
What is the cycle of convection in the Earth's mantle?
Hot material rises, cools, moves laterally, sinks, warms, and rises again.
How do rocks behave when they are subjected to tectonic forces?
They bend to form folds rather than break along faults.
What is a characteristic of joint patterns?
They generally have a characteristic geometry and a regular spacing.
What can the edges of clay particles be charged?
Positively or negatively charged.
What are the three main modes of joint development?
Tectonic joints, stress relief joints, and cooling joints.
What defines clastic sedimentary rocks?
They are defined by their composition and the process of sedimentation.
What does Bowen's Reaction Series compare to?
The weathering stability series.
What are the most important chemical processes of weathering?
Hydrolysis and solution.
What mineral is specifically mentioned in relation to clay-water interaction?
Kaolinite.
What is the typical external surface area of Montmorillonite?
50 - 120 m²/gm.
What is structural geology?
The study of the three-dimensional distribution of rock units and their deformational histories.
What does structural geology focus on?
The arrangement and deformation of rocks.
What visual characteristic do foliated metamorphic rocks commonly display?
Alternating dark and light colored bands reflecting the concentration of minerals.
What factors influence the particle sizes of transported soils?
Transportation agents such as streams and wind.
How can transported soils be categorized?
Based on the mode of transportation and deposition.
What is a symmetrical anticline?
A fold where the limbs are mirror images of each other.
What is studied in soil formations?
The processes and deposits that create soil.
How is strike defined in geology?
The azimuth or direction of the feature in the horizontal plane.
What is a less common type of soil in Hong Kong?
Grade VI Residual Soils.
Which website features events and activities happening in Sai Kung?
Sai Kung District Council.
Under what conditions do Desert Roses typically form?
In arid sandy conditions, such as the evaporation of a shallow salt basin.
What are precipitates in sedimentary rocks?
Sedimentary rocks that resulted from chemical precipitation in marine or fresh water environments.
What is the study of plate movements called?
Plate tectonics.
What is the nature of the net interparticle force in a dispersed fabric?
The net interparticle force is repulsive.
What is the charge condition of clay particles in dry conditions?
Can be either positive or negative.
What shape can cooling joints form?
They may form hexagonal columns.
What causes metamorphic rocks to form?
The alteration of existing rocks due to heat, pressure, or chemically active fluids.
What is the typical size range of Desert Rose formations?
From pea-sized to 4 inches (10 cm) in diameter.
What is marble primarily composed of?
Crystalline calcite minerals from limestone.
What geological process is driven by heat retained in thick ash layers?
Post-emplacement hydrothermal alteration processes.
What is the chemical formula for Montmorillonite?
Si8Al4O20(OH)4·nH2O.
Where can you find information about rock minerals?
What shape do Montmorillonite minerals typically have?
Film-like shape.
What is the website for the AFCD Lions Nature Education Centre?
What causes the red or yellow color in residual soils?
The presence of iron oxides.
Who is associated with the study of noncrystalline clay?
Mitchell, 1993.
What is the AFCD Lions Nature Education Centre?
A facility focused on nature education and conservation.
What causes water molecules to diffuse toward the interlayer?
The concentration difference of cations.
What does crystalline texture indicate?
Rocks are mostly composed of mineral crystals that have developed in the rock itself.
What does Rock Mechanics study?
The behavior of rock materials under various conditions.
Who provided the geological map of Hong Kong?
Hong Kong Geological Survey.
How do clay minerals affect soil properties?
They influence water retention, nutrient availability, and soil structure.
What is the typical external surface area of Montmorillonite compared to Illite?
Montmorillonite: 50 - 120 m²/gm; Illite: 700 - 840 m²/gm.
What are transported soils?
Soils that are moved and deposited in other places.
What engineering concern is associated with folds?
Influences on dam stability.
What is the typical thickness range of Kaolinite layers?
0.05 to 2 μm.
What are residual soils?
Soils that form in place from the weathering of bedrock.
What characterizes an asymmetrical anticline?
One limb is steeper than the other.
What is the relationship between minerals and rocks?
Rocks are composed of one or more minerals.
Where does most volcanic and mountain-building activity occur?
At the intersections of large lithospheric plates.
What type of igneous rock is granite classified as?
Intrusive or plutonic.
What are the three main types of rocks?
Igneous, sedimentary, and metamorphic.
What is the definition of Specific Surface (S_s)?
It is the surface area per unit mass of a material, often expressed in cm²/g.
What is required to balance the surface charges of clay particles?
Different amounts of cations.
What is the structural arrangement of silica tetrahedra in some minerals?
They can form hexagonal holes.
What happens to the original minerals in metamorphic rocks?
Some or all of the original minerals are replaced by new minerals.
What other minerals may form rosette clusters besides gypsum and baryte?
Celestine and other bladed evaporite minerals.
What aspect of rock joints will be discussed later?
The shear strength of rock joints.
What units are commonly used to express Specific Surface?
cm²/g.
How do igneous rocks form?
When hot, molten rock (magma) cools and solidifies.
What are aeolian soils?
Soils transported and deposited by the wind.
What is the chemical composition of quartz?
Silicon dioxide (SiO2).
What is a characteristic feature of clay minerals in geological formations?
They are often found in weak planes.
What type of bond is involved in clay-water interaction?
Hydrogen bond.
What is the significance of the natural water content in relation to swelling potential?
It must be around the plastic limit (PL).
What is the radius of a hydrated Na+ ion?
0.358 nm.
What does 'interlayer' interaction refer to?
Interactions between layers of clay particles.
What does 'interparticle' interaction refer to?
Interactions between individual clay particles.
What is the typical external surface area of Illite?
65 - 100 m²/gm.
What is the typical width range of Kaolinite layers?
0.1 to 4 μm.
Which website provides information on Sai Kung's local dining options?
TripAdvisor.
What type of sedimentary rock is referred to as 頁岩?
Shale.
What is the chemical formula for feldspar?
2 KAlSi3O8.
What is a fold in geological terms?
A bend of a planar structure, such as a bedding plane, in a rock.
What is an overturned anticline?
An anticline where one limb has been tilted beyond vertical.
What is the thickness range of the Earth's crust?
25 to 75 km thick.
How do residual soils differ from transported soils?
Residual soils form from the underlying bedrock, while transported soils are moved from their original location.
What are cooling joints?
Joints that develop as a result of cooling and contraction in granitic and volcanic rocks following their emplacement.
What occurs during ion hydration in clay?
Cations become fully hydrated, resulting in repulsive forces and expanding clay layers.
What is the purpose of water molecules diffusing toward the interlayer?
To equalize concentration.
Who operates the Lions Nature Education Centre?
The Agriculture, Fisheries and Conservation Department (AFCD).
What is the typical external surface area of Kaolinite?
10 - 20 m²/gm.
What is the general understanding of residual soils in geotechnical engineering?
It is insufficient compared to the understanding of transported soils.
What type of rock is Siltstone?
A clastic sedimentary rock that shows thin sedimentary layers.
What is a key characteristic of Conglomerate?
It contains rounded lithic clasts.
Who manages the AFCD Lions Nature Education Centre?
The Agriculture, Fisheries and Conservation Department (AFCD).
What is the dip angle of a geologic feature?
The acute angle between the feature and a reference plane, usually the horizontal.
What website offers insights into Sai Kung's marine life and conservation?
Hong Kong Marine Conservation Society.
What is a key focus of residual soils in Hong Kong?
The characteristics and formation of residual soils in that region.
What engineering problem can swelling rocks cause during tunnel construction?
Serious problems when materials are de-stressed during excavation.
What type of minerals does Illite belong to?
Mica-like minerals.
What is the primary focus of the interaction of water and clay minerals?
The behavior and properties of clay minerals when in contact with water.
Who authored 'Engineering Geology'?
R.E. Goodman.
What are the two types of water mentioned in relation to clay?
Adsorbed layers and bulk water.
How do biological sedimentary rocks form?
They form when large quantities of living plants or organisms die and accumulate, then their remains are broken down, compressed, and cemented to form rock.
What is a popular website for exploring Sai Kung's outdoor activities?
Sai Kung Outdoor Recreation Centre.
What is an example of a metamorphic rock that shows foliation?
Graphite schist.
What happens to hot matter from the mantle in the context of plate tectonics?
It rises, causing plates to form and diverge.
How are chemical sedimentary rocks formed?
By chemical precipitation from solutions when water dissolves minerals and carries them away, leading to deposition when the water evaporates or becomes oversaturated.
What type of ions are attracted to the negatively charged clay surface?
Cations.
What type of audience does the AFCD Lions Nature Education Centre cater to?
Students, educators, and the general public interested in nature.
What type of ions are repelled by the negatively charged clay surface?
Anions.
What characterizes a dispersed fabric in clay structure?
Particles are spread out and not clumped together.
What gives foliated metamorphic rocks a silky or shiny appearance?
The presence of micas.
What are the types of soils found in Hong Kong?
What characterizes Saprolites in Hong Kong?
They have a soil-like texture with rock texture preserved.
What is the origin of colluvial soils in Hong Kong?
They mainly originate from landslides.
Where is the study of residual soils particularly relevant?
In Hong Kong.
What is a flocculated fabric in clay structure?
A type of clay structure where particles are clumped together.
What is the relationship between dip and strike?
Dip and strike are at right angles to each other.
What is the chemical formula for a silica tetrahedron?
SiO4.
How are metamorphic rocks formed?
When a pre-existing rock is subjected to high temperature, high pressure, hot and mineral-rich fluid, or a combination of these conditions.
What shape do the crystals of Desert Rose typically resemble?
A rose blossom.
What drives the movement of tectonic plates?
Convection cells that circulate the Earth's internal heat.
Where can you find reviews and recommendations for Sai Kung's attractions?
Google Maps.
What is a commonly occurring intrusive rock in Hong Kong?
Granite.
How do shear or fault zones compare to intact rock?
They might be weaker and more permeable than the intact rock.
What is the typical orientation of cooling joints?
They are typically perpendicular to the cooling surface.
What role does water play in the plasticity of clay?
Water increases the plasticity of clay, allowing it to be molded and shaped.
What characterizes a reverse or thrust fault?
The hanging wall moves up relative to the footwall, typically at a steep angle.
How is Specific Surface (S_s) calculated?
S_s = surface area / mass.
What is a series of closely spaced, approximately parallel faults called?
A shear or fault zone.
What happens when four oxygen atoms in silica tetrahedra are replaced?
They can be replaced with hydroxyls or combined with positive ions.
What types of original rocks can become metamorphic rocks?
Igneous, sedimentary, or earlier metamorphic rocks.
Why is Illite sometimes referred to as hydrous mica?
Because its basic structure is very similar to mica.
How are alluvial soils formed?
They are transported by running water and deposited along streams.
What does equigranular granite mean?
Mineral grains are of approximately the same size.
What is the focus of Irfan's 1996 study?
Mineralogy, Fabric Properties and Classification of Weathered Granites in Hong Kong.
How is slate formed?
By the alteration of shale or mudstone through low-grade regional metamorphism.
What is the fixed basal spacing of Illite in the presence of polar liquids?
10 Å (no interlayer swelling).
How does water affect the structure of clay minerals?
Water can cause swelling, shrinkage, and changes in the physical properties of clay minerals.
What are glacial soils?
Soils formed by the transportation and deposition of glaciers.
What process leads to the formation of sedimentary rocks?
The accumulation and compaction of sediment.
What is the formula for a double tetrahedral unit in silicates?
(Si2O10) - 4.
What is the relationship between Specific Surface and particle size?
Specific Surface (S_s) is inversely proportional to particle size.
Which type of Desert Rose usually has better defined, sharper edges?
Gypsum roses.
What are some examples of surface-related forces?
Van der Waals forces and capillary forces.
What happens to clay minerals when they dry out?
They can shrink and become hard, losing their plasticity.
What causes charge deficiencies in Illite?
Replacement of Si4+ by Al3+ or Fe3+, and Al3+ by Mg2+.
What is the title of the book by Holtz, Kovacs, and Sheahan?
An Introduction to Geotechnical Engineering.
What do joints and fault zones create in rock mass?
Weak planes that strongly influence the engineering behavior of the rock mass.
What is the chemical formula for calcite?
CaCO3.
What type of rock is slate?
A fine-grained, foliated metamorphic rock.
What distinguishes nonfoliated metamorphic rocks?
They did not develop foliation as a result of their metamorphism.
What is the chemical formula for the Gibbsite sheet?
Al₂(OH)₆.
What is the website for Hong Kong slope safety?
What is the typical width and thickness of Illite?
Width: 0.1 ~ several μm, Thickness: ~ 30 Å.
How does foliation develop in metamorphic rocks?
It develops when platy or prismatic minerals are compressed and aligned under extreme pressure.
What are the most important minerals in the silicate group?
Quartz, feldspar, mica, chlorite, amphibole, pyroxene, olivine, serpentine, talc, and clay minerals.
What type of bond is formed between water molecules?
Hydrogen bonds.
Which clay mineral is mentioned in relation to negative gold sol?
Kaolinite.
What happens to salts in an aqueous solution?
They dissociate into ions and become hydrated.
What do hexagonal joints in tuff indicate about the cooling process?
They indicate that the tuff ponded in a large depression and cooled relatively slowly.
What type of rock is shale?
A fine-grained clastic sedimentary rock.
What is an oblique-slip fault?
A fault that has both vertical and horizontal movement.
What is the title of the book by Mitchell and Soga?
Fundamentals of Soil Behavior.
How common are earthquakes beyond plate boundaries?
They are less common.
What types of lithosphere do tectonic plates contain?
Continental lithosphere, oceanic lithosphere, or a combination of both.
What characterizes foliated metamorphic rocks?
They are banded or laminated due to the flattening of mineral grains under extreme temperatures and pressure.
What is a strike-slip fault?
A fault where the movement is horizontal, with blocks sliding past each other.
What is hydration in the context of salts in solution?
The process where water molecules surround and interact with ions from dissolved salts.
What are lacustrine soils?
Soils formed by deposition in quiet lakes.
What characterizes coarse grain crystal tuff?
It contains mainly crystal fragments.
What defines a hinge fault?
A fault characterized by a bending or folding of rock layers.
Who wrote 'An Introduction to Clay Colloid Chemistry'?
H. Van Olphen.
What is the primary composition of shale?
Compacted silt and clay-size mineral particles, commonly referred to as 'mud'.
What are the two main types of igneous rocks?
Intrusive (plutonic) and extrusive (volcanic) rocks.
What is the typical shape of quartz crystals?
Hexagonal and prismatic.
How is the charge deficiency in Illite balanced?
By potassium ions between layers.
How are sedimentary rocks formed?
From eroded fragments of pre-existing rocks or skeletal fragments of once-living organisms.
Is marble a foliated or nonfoliated metamorphic rock?
Nonfoliated.
What is the angle of a gentle fault?
Typically has a more gentle angle compared to steep faults.
What is slaty cleavage?
The ability of slate to break smoothly along planes of foliation.
What are clastic sedimentary rocks made of?
Fragments (clasts) of pre-existing rocks.
What is hydrolysis in chemical weathering?
It is the reaction with water that involves the solubility of silica and alumina.
What are smaller scale curved or concentric joints associated with corestone development called?
Exfoliation joints.
What characterizes non-foliated metamorphic rocks?
They display a massive structure.
What is plagioclase feldspar rich in?
Sodium or calcium.
What is the relationship between cations and hydroxide ions in the octahedral sheet?
One cation is surrounded by six O or OH.
Where do marine soils form?
They are formed by deposition in the seas.
What is quartz commonly called?
Silica.
How many cationic spaces are filled in the Gibbsite sheet?
2/3 of the cationic spaces are filled.
How are colluvial soils formed?
By the movement of soil from its original place by gravity, such as during a landslide.
What category of sedimentary rocks does shale belong to?
Mudstones.
How are intrusive igneous rocks formed?
When rising magma is trapped deep within the Earth and cools slowly.
In what forms do granitic rocks occur?
As plutons, dykes, or sills.
How does the presence of iron oxides affect the appearance of Desert Roses?
It gives the rosettes a rusty tone.
What is the structure of foliated metamorphic rocks?
They exhibit a platy or sheet-like structure.
What causes foliation in slate?
The parallel orientation of platy minerals such as clay minerals and mica.
Name two minerals classified as 'others'.
Gypsum and halite.
What reaction occurs when marble is exposed to dilute hydrochloric acid?
It produces gas bubbles (effervescence).
Where does magma originate?
Deep within the Earth near active plate boundaries or hot spots.
What is unloading in the context of physical weathering?
It refers to processes like uplift, erosion, or change in fluid pressure.
In the Gibbsite sheet, how many aluminum ions surround one hydroxide ion?
Two aluminum ions.
What do the foliation patterns in metamorphic rocks reflect?
The direction in which pressure was applied.
What is the chemical formula for halite?
NaCl.
What is a characteristic texture of intrusive igneous rocks?
Coarse-grained texture with interlocking minerals.
What does 'fissile' mean regarding shale?
The rock readily splits into thin pieces along the laminations.
What is the chemical composition of gypsum?
CaSO4·2H2O.
How are non-foliated metamorphic rocks formed?
By contact metamorphism around intrusive igneous rocks.
Where can you find a YouTube video related to geology?
What type of cementation occurs in soils formed from volcanic rocks?
Cementation formed by iron oxides.
What is the typical weathering depth for soils formed from volcanic rocks?
Up to 20 m.
What is plagioclase feldspar used for?
In ceramics.
What causes stress relief joints to develop in rocks?
Relaxation of confining pressure following erosion of overlying layers.
What is the angle of a steep fault?
Typically has a more steep angle compared to gentle faults.
What process leads to the formation of clastic sedimentary rocks?
Sediment is buried, compacted, and cemented.
How easily can marble be scratched?
It can be easily scratched with a knife.
What is the website for the Hong Kong UNESCO Global Geopark?
Into how many groups are sedimentary rocks sub-divided?
Three groups: clastic, biological, and chemical.
What is the chemical formula for the Brucite sheet?
Mg₃(OH)₆.
Why is slate popular in construction?
Due to its durability and attractive appearance.
What minerals predominantly compose granitic rocks?
Feldspar and quartz, with subordinate amphiboles and micas.
What is alkali feldspar primarily composed of?
Potassium aluminium silicate (K,Na)AlSi3O8.
What are the effects of thermal expansion and contraction in weathering?
They contribute to the physical breakdown of rocks.
What type of cementation occurs in soils formed from granitic rocks?
Cementation formed by iron oxides.
Where is marble buried beneath thick sediments in Hong Kong?
In the Yeun Long and Ma On Shan areas.
What does chelation involve in the weathering process?
The complexing and removal of metal ions.
What type of rock is marble and how is it formed?
Marble is a metamorphic rock altered from limestone.
What colors can quartz exhibit due to impurities?
Violet, pink, and orange.
What are large-scale stress relief joints that are subparallel to the topography called?
Sheeting joints.
How can individual minerals in granitic rocks be identified?
Generally with the naked eye.
What is the chemical reaction when marble reacts with hydrochloric acid?
2HCl + CaCO3 → CaCl2 + H2O + CO2.
What is quartz used for?
Making glass.
In which type of rocks are sheeting joints commonly developed in Hong Kong?
Granitic rocks.
What is one common use of alkali feldspar?
As a raw material to make porcelain.
Where can you learn about Hong Kong's geology over 400 million years?
What property of slate is exploited for manufacturing?
The ability to produce thin sheets that can be used in various projects.
What are the characteristics of how shale breaks?
Shale breaks into thin pieces with sharp edges.
What is the typical appearance of alkali feldspar crystals?
Stubby prisms.
What is a commonly occurring intrusive rock in Hong Kong?
Granite.
How many cationic spaces are filled in the Brucite sheet?
All cationic spaces are filled.
What is the typical weathering depth for soils formed from granitic rocks?
Up to 60 m or more.
What reaction describes the dissolution of calcium carbonate in water?
CO2 + H2O + CaCO3 → Ca2+ + 2 HCO3-.
What colors are commonly associated with alkali feldspar?
Pink to white.
What determines the naming of clastic sedimentary rocks?
The grain size and shape of the clasts.
In the Brucite sheet, how many magnesium ions surround one hydroxide ion?
Three magnesium ions.
What is the characteristic of the mineral grains in marble?
The mineral grains are interlocking.
What texture do the minerals in granitic rocks exhibit?
Crystalline with an interlocking texture.
Is corestone formation common in soils formed from granitic rocks?
Yes, it is very common.
How does cation exchange contribute to weathering?
It is important for the formation of clay minerals.
How are extrusive igneous rocks formed?
When magma is erupted at or near the Earth's surface and cools quickly.
What geological feature is formed by the dissolution of calcium carbonate?
Karst topography.
What is siltstone composed of?
Silt-sized grains.
What colors can shale occur in?
Red, brown, green, gray, and black.
What is the common color of unweathered granite?
Pinkish grey or light grey.
What are the dominant minerals in soils formed from the weathering of volcanic rocks?
Kaolinite, quartz, halloysite, and occasional K-feldspar.
What is the chemical composition range for plagioclase feldspar?
From NaAlSi3O8 to CaAl2Si2O8.
What role does climate play in the weathering process?
It determines the amount of water and temperature affecting weathering.
Where is shale commonly found?
In sedimentary basins worldwide.
What happens to pre-existing rocks during contact metamorphism?
They are essentially baked by the heat without being subjected to intense pressure.
What is the typical appearance of plagioclase feldspar crystals?
Stubby prisms.
What color is plagioclase feldspar generally?
White to grey.
Why are underground hollows (caverns) problematic for construction?
They are troublesome to foundation design.
What are two common types of extrusive igneous rocks?
Lava and tuff.
Can you name examples of non-foliated metamorphic rocks?
Quartzite and marble.
In which types of rocks are micas commonly found?
Intrusive igneous, sedimentary, and metamorphic rocks.
What is the typical crystal form of amphiboles?
Prismatic or needle-like crystals.
Why is interlayer swelling important in engineering practice?
It relates to expansive clay.
What type of joint sets are commonly found in granite on Po Toi Island?
At least two orthogonal, subvertical joint sets.
What is a common member of the amphibole group?
Hornblende.
What causes the pink color in pink marble?
The pink color is most likely derived from iron.
What is carbonation in the context of chemical weathering?
It is the combination of carbonate ions, such as the reaction with CO2.
What is the typical color of unweathered tuff?
Dark grey.
What is sandstone composed of?
Sand-sized grains.
What are the typical dimensions of Montmorillonite particles?
Width: 1 or 2 μm, Thickness: 10 Å.
How persistent can stress relief joints in granitic rocks be?
They may extend for several hundreds of meters.
What local feature may stress relief joints facilitate the formation of?
Exfoliation joints associated with corestone development.
What distinguishes biotite from muscovite?
Biotite is dark (black or brown), while muscovite is light-colored or clear.
What does tuff contain?
Fragments of minerals, glass, pumice, and/or pre-existing rocks.
How is tuff classified?
Based on the relative components of the various fragments.
What structural feature may tuff exhibit?
A welding structure.
How do micas typically form their crystals?
Flat, book-like crystals that split into individual sheets.
What type of lustre does plagioclase feldspar have?
Vitreous lustre.
What happens to crystals or fragments of pre-existing rocks during the formation of clastic sedimentary rocks?
They are loosened by weathering and transported to a deposition site.
What is the significance of alternate wetting and drying in physical weathering?
It contributes to the breakdown of rocks through repeated expansion and contraction.
What is the most common sedimentary rock?
Shale.
What characteristic do stress relief joints in granite produce?
Gently curved joints that parallel the slope surface.
What factors can affect the weathering process?
Climate, topography, features of parent rocks, and biological reactions.
What characteristic may some tuff display?
Columnar jointing.
Is corestone formation common in soils formed from volcanic rocks?
No, it is not common except in coarse ash tuff.
What elements do amphibole minerals generally contain?
Iron, magnesium, calcium, aluminium, silicon, oxygen, and water.
