Quick Review Flashcards - Click to flip and test your knowledge!
Question
How is a 'rock' defined in the context of the earth's crust?
Answer
An aggregate of minerals forming a more or less definite unit of the crust.
Question
Beyond hard solids like granite, what other materials are classified as 'rocks'?
Answer
Soft and loose particles such as sand, silt, and clay.
Question
In terms of chemical composition, how do rocks differ from minerals?
Answer
Minerals have a definite chemical composition, while rocks do not.
Question
What is the relationship between minerals and rocks regarding their structure?
Answer
Minerals are organised to form rocks, making rocks aggregates of one or more minerals.
Question
Which two mineral elements are most abundant specifically in the Earth's crust?
Answer
Silicon and aluminium.
Question
Which three elements are most abundant in the Earth as a whole?
Answer
Iron, silica, and magnesium.
Question
What are the four chief mineral groups?
Answer
Silicates, carbonates, sulphides, and metallic minerals.
Question
On what basis are rocks primarily classified into three main types?
Answer
Their mode of origin.
Question
What are the three main types of rocks based on their origin?
Answer
Igneous, Sedimentary, and Metamorphic.
Question
What is the etymological origin and meaning of the word 'Igneous'?
Answer
It is derived from the Latin word 'ignis', meaning fire.
Question
How are igneous rocks formed?
Answer
Through the cooling, solidification, and crystallisation of hot molten magma.
Question
Why are igneous rocks referred to as 'primary rocks'?
Answer
They were the first rocks to be formed and provide the basis for all other rock types.
Question
What term is used for igneous rocks composed primarily of alumino-silicate minerals like quartz and feldspar?
Answer
Sialic rocks.
Question
How does the rate of cooling affect the crystal size in igneous rocks?
Answer
Slow cooling allows for the formation of large crystals, while rapid cooling results in fine-grained textures.
Question
Why are igneous rocks generally less affected by chemical weathering?
Answer
They are compact and water does not easily percolate through them.
Question
In what specific geological regions are igneous rocks most commonly found?
Answer
Volcanic regions.
Question
What defines an 'extrusive' igneous rock?
Answer
A rock formed by the cooling of molten magma on the Earth's surface.
Question
What is an alternative name for extrusive igneous rocks?
Answer
Volcanic rocks.
Question
Give a common example of an extrusive igneous rock found in lava plateaus.
Answer
Basalt.
Question
What defines an 'intrusive' igneous rock?
Answer
A rock formed when magma solidifies within the Earth's crust.
Question
What is an alternative name for intrusive igneous rocks due to their deep-seated formation?
Answer
Plutonic rocks.
Question
What are 'hypobyssal' rocks?
Answer
Igneous rocks formed when magma cools at intermediate depths, often forming sills and dykes.
Question
Intrusive Rock Form: Batholith
Answer
Definition: Deep-seated, dome-shaped intrusions with no definite floor, often forming the cores of mountain ranges.
Question
Intrusive Rock Form: Laccolith
Answer
Definition: An intrusion where magma spreads between layers, creating a dome-shaped upper surface and a flat bottom.
Question
Intrusive Rock Form: Sill
Answer
Definition: A horizontal layer of intrusive rock formed when magma flows between existing rock layers.
Question
Intrusive Rock Form: Dyke
Answer
Definition: A vertical or steeply inclined intrusion formed when magma fills existing cracks or fissures.
Question
Intrusive Rock Form: Neck
Answer
Definition: A volcanic plug formed when the passage of an extinct volcano is filled with solidified magma.
Question
What defines an 'Acid' igneous rock in terms of silica content?
Answer
A silica content between $65\%$ and $85\%$.
Question
What defines a 'Basic' igneous rock in terms of silica content?
Answer
A silica content between $40\%$ and $60\%$.
Question
Compare the colour and weight of 'Basic' igneous rocks to 'Acid' igneous rocks.
Answer
Basic rocks are typically heavy and dark in colour, while acid rocks are generally lighter.
Question
How are sedimentary rocks formed?
Answer
From the accumulation and lithification of sediments derived from other rocks, plants, or animal remains.
Question
What is 'lithification'?
Answer
The process that turns loose sediments into hard rock.
Question
What is 'cementation' in the context of sedimentary rock formation?
Answer
The bonding together of compacted sediments by natural materials like calcium compounds, silica, or iron.
Question
What are the three main stages of lithification?
Answer
Evaporation, compaction, and cementation.
Question
Why are sedimentary rocks also known as 'stratified rocks'?
Answer
They are formed in distinct layers or strata.
Question
Which rock type is the only one to contain fossils?
Answer
Sedimentary rocks.
Question
What is the difference between 'clastic' and 'non-clastic' sedimentary rocks?
Answer
Clastic rocks form from fragments of other rocks, while non-clastic rocks form via chemical or organic processes.
Question
Provide an example of a mechanically formed sedimentary rock.
Answer
Sandstone (or shale, clay, conglomerate).
Question
How do 'chemically formed' sedimentary rocks originate?
Answer
Through the direct precipitation of mineral matter from a solution, often via evaporation.
Question
Provide an example of a chemically formed sedimentary rock.
Answer
Gypsum (or rock salt, potash).
Question
What is the primary constituent of 'calcareous' sedimentary rocks?
Answer
Calcium carbonate (lime) derived from skeletons and shells.
Question
What are 'carbonaceous' rocks?
Answer
Organically formed rocks derived from vegetable matter, such as peat, lignite, and coal.
Question
Name the four stages of vegetable matter transformation into coal.
Answer
Peat, lignite, bituminous, and anthracite.
Question
Sedimentary Agent: Riverine
Answer
Definition: Rocks formed by alluvial deposits brought by flowing stream water.
Question
Sedimentary Agent: Lacustrine
Answer
Definition: Rocks formed by successive periods of deposition on the bed of a lake.
Question
Sedimentary Agent: Aeolian
Answer
Definition: Rocks formed by sand particles transported and deposited by winds, such as loess.
Question
What is 'petrification'?
Answer
The multi-step process by which organic remains are turned into fossils within sedimentary rocks.
Question
What does the term 'metamorphism' mean literally?
Answer
Change in form.
Question
What are the two primary factors that cause metamorphism?
Answer
High temperature (heat) and great pressure.
Question
Why do metamorphic rocks lack fossils even if the original rock contained them?
Answer
The fossils are destroyed during the intense heat and pressure of the metamorphic process.
Question
What is 'Thermal Metamorphism'?
Answer
Rock transformation driven primarily by the influence of high temperatures, such as contact with magma.
Question
What is 'Dynamic Metamorphism'?
Answer
Transformation caused mainly by pressure at great depths, often resulting in mineral banding called foliation.
Question
What is 'foliation' in metamorphic rocks?
Answer
The arrangement of minerals in a series of bands due to pressure during metamorphism.
Question
What is 'Regional Metamorphism'?
Answer
Large-scale transformation associated with mountain-building processes where rocks are buried deep and subjected to intense heat and pressure.
Question
Into what metamorphic rock does limestone transform?
Answer
Marble.
Question
Into what metamorphic rock does sandstone transform?
Answer
Quartzite.
Question
Into what metamorphic rock does shale transform?
Answer
Slate.
Question
Into what metamorphic rock does coal transform?
Answer
Graphite.
Question
Into what metamorphic rock does granite transform?
Answer
Gneiss.
Question
Into what metamorphic rock does basalt transform?
Answer
Schist.