Geomorphology Flashcards
How are block mountains formed?
Through large-scale faulting where large blocks of earth are broken and displaced vertically or horizontally.
What are the uplifted and lowered blocks called in block mountain formation?
Uplifted blocks are horsts, and lowered blocks are graben.
How are fold mountains formed?
When sedimentary rock strata in geosynclines are subjected to compressive forces.
Give an example of a block mountain.
The Vosges mountains in Eastern France.
Give examples of fold mountains.
The Alps (Europe), Appalachians (North America), Andes (South America).
What is the ‘solution’ process in chemical weathering?
The dissolving of minerals by water, especially rainwater containing carbon dioxide (which makes it a weak acid).
Why is solution a particularly potent weathering process in limestone regions?
Because rainwater attacks and dissolves the calcium carbonate which chiefly forms limestone, widening joints and creating features like caves.
What is ‘oxidation’ in chemical weathering?
The reaction of oxygen (from air or water) with minerals in the rock, such as iron turning into iron oxide (rust).
How does oxidation weaken rocks?
The product (e.g., iron oxide) often crumbles easily and is more easily eroded than the original mineral, loosening the rock structure.
What is the difference between magma and lava?
Magma is molten rock material within the Earth (specifically mentioned as upper mantle portion); Lava is magma once it starts moving towards or reaches the Earth’s surface.
What materials can be ejected during a volcanic eruption?
Lava flows, pyroclastic debris, volcanic bombs, ash, dust, and gases (like nitrogen compounds, sulfur compounds, chlorine, hydrogen, argon).
What are the two main types of seismic waves?
Body waves (travel through Earth’s interior) and Surface waves (travel along the surface).
What are the two types of body waves, and which arrives first?
P-waves (primary) and S-waves (secondary). P-waves are faster and arrive first.
How do particles vibrate in P-waves?
Parallel to the direction of wave propagation (compressional).
How do particles vibrate in S-waves?
Perpendicular to the direction of wave propagation (transverse).
How is black soil typically formed in the Deccan Plateau region of India?
By the weathering of fissure volcanic rock (basaltic rock) under moderate rainfall conditions.
Under India’s MMDR Act, 1957, is sand classified as a major or minor mineral?
Minor mineral.
Which level of government primarily regulates minor minerals in India?
State governments are empowered to frame rules regarding leases and other matters for minor minerals.
Which level of government has jurisdiction over controlling illegal mining in India?
State governments.
What two major geological/climatic processes have influenced the evolution of organisms?
Continental drift and Glacial cycles.
What was the name Alfred Wegener gave to the proposed single supercontinent?
PANGAEA.
What were the names of the two large landmasses Pangaea first broke into?
Laurasia (northern component) and Gondwanaland (southern component).
List five major forces/phenomena responsible for bringing dynamic changes to the Earth’s surface.
Electromagnetic radiation (solar energy), Geothermal energy, Gravitational forces (tides), Plate movements (tectonics), Earth’s Rotation (Coriolis effect).
How does Earth’s rotation influence surface dynamics?
Causes the Coriolis effect, deflecting wind and ocean currents, influencing weather patterns.
How does Earth’s revolution influence surface dynamics?
Causes the change of seasons by altering the angle/duration of solar insolation received at different latitudes.
What is soil conservation?
A methodology to maintain soil fertility, prevent soil erosion and exhaustion, and improve degraded soil conditions.
What is recommended for agricultural use on lands with a slope gradient of 15-25 percent?
Cultivation should ideally be avoided, but if necessary, terraces should be carefully constructed.
List some remedial measures often adopted to reduce soil erosion.
Contour bunding, contour terracing, regulated forestry, controlled grazing, cover cropping, mixed farming, and crop rotation.
How can gully erosion be controlled or prevented?
Finger gullies can be eliminated by terracing. In bigger gullies, constructing check dams, gully plugging, terracing, or planting cover vegetation can reduce water’s erosive velocity.
How can cultivable lands in arid and semi-arid areas be protected from sand dune encroachment?
By developing shelter belts of trees, sand fences, wind breaks, and practicing agro-forestry.
What should be done with land not suitable for cultivation?
It should be converted into pastures for grazing.
What materials reaching the ground are included during volcanic eruptions?
Lava flows, pyroclastic debris, volcanic bombs, ash and dust and gases such as nitrogen compounds, sulphur compounds and minor amounts of chlorene, hydrogen and argon.
What are the main gases dissolved in magma?
Water vapour, carbon dioxide, and sulphur gases, with lesser amounts of hydrogen, hydrochloric acid, and hydrofluoric acid.
What type of lava is typically very fluid and hot when erupted, forming volcanoes that are not steep?
Basaltic lava.
Under what condition might a typically low-explosivity basaltic volcano become explosive?
If water somehow gets into the vent.
What type of rock forms when volcanic lava cools?
Igneous rocks.
What is the difference between volcanic and plutonic igneous rocks?
Volcanic rocks form from lava cooling at the surface, while plutonic rocks form from magma cooling in the crust.
What are dykes in geology?
Wall-like intrusive structures formed when lava solidifies in cracks or fissures, often nearly perpendicular to the ground. These are common in western Maharashtra area and considered feeders for the Deccan Traps.
What does the Mercalli scale measure regarding earthquakes?
The intensity of an earthquake based on the visible damage caused by the event. Its range is 1-12.
What does the Richter scale measure regarding earthquakes?
The magnitude of an earthquake, related to the energy released during the quake. It uses absolute numbers, 0-10.
How much does the wave amplitude increase for each whole number increase on the Richter scale?
The wave amplitude increases by 10 times (e.g., amplitude at magnitude 6 is 10 times greater than at magnitude 5).
Approximately how much does the energy released increase for each whole number increase on the Richter scale?
About 31.7 times.
How are sedimentary rocks formed?
From fragments of pre-existing rocks (igneous, sedimentary, metamorphic) that are weathered, transported, deposited (often in layers by agents like water or wind), and then lithified (compacted and cemented).
Can sedimentary rocks contain fossils?
Yes, they may contain fossils of plants, animals, and other microorganisms that lived when the sediments were deposited.
What is the correct sequence of water erosion processes mentioned?
Splash erosion -> Sheet erosion -> Rill erosion -> Gully erosion.
What is splash erosion?
The initial stage where raindrop impact on bare soil breaks up aggregates and splashes soil particles.
What is sheet erosion?
Removal of a thin, uniform layer of soil by runoff water, often on level land after heavy rain; it can be harmful as it removes fertile topsoil.
