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Which of the following islands is entirely volcanic in origin and located over a ‘Hotspot’?
Hawaii is the premier example of hotspot volcanism located in the middle of the Pacific Plate. A mantle plume—a localized column of intense heat—melts the overlying plate to create magma. Because the hotspot remains fixed while the tectonic plate moves northwestward, it creates a chronological trailRead more
Hawaii is the premier example of hotspot volcanism located in the middle of the Pacific Plate. A mantle plume—a localized column of intense heat—melts the overlying plate to create magma. Because the hotspot remains fixed while the tectonic plate moves northwestward, it creates a chronological trail of islands. The Big Island of Hawaii is currently situated directly over the plume and remains active. Older islands, like Kauai, have moved away from the heat source and are now extinct. This geographic process demonstrates the motion of tectonic plates relative to the Earth’s deep interior.
See lessWhich of the following is an example of a ‘Parasitic Cone’ in volcanic geomorphology?
In volcanic geomorphology, a parasitic cone is a secondary eruptive unit located on the slopes of a larger stratovolcano. It is "parasitic" because it shares the same underlying magma source as the main volcano. When pressure increases and the primary conduit is clogged by solidified lava, magma isRead more
In volcanic geomorphology, a parasitic cone is a secondary eruptive unit located on the slopes of a larger stratovolcano. It is “parasitic” because it shares the same underlying magma source as the main volcano. When pressure increases and the primary conduit is clogged by solidified lava, magma is diverted through lateral fissures. This results in an eruption on the mountain’s side rather than at the summit. Mount Etna in Sicily is geographically famous for having hundreds of these cones, which create a rugged, multi-peaked profile and increase the geographical area affected by lava flows.
See lessA ‘Lava Plateau’ like the Deccan Traps is formed by which type of volcanic eruption?
Lava plateaus are created by extensive fissure eruptions, which involve the quiet, effusive release of low-viscosity basaltic magma. Instead of building a tall cone, the lava flows like water, flooding vast depressions and plains. Over time, successive flows accumulate, building a massive, flat-toppRead more
Lava plateaus are created by extensive fissure eruptions, which involve the quiet, effusive release of low-viscosity basaltic magma. Instead of building a tall cone, the lava flows like water, flooding vast depressions and plains. Over time, successive flows accumulate, building a massive, flat-topped plateau. The Deccan Traps in India were formed this way approximately 66 million years ago. These eruptions are often associated with mantle plumes or continental rifting. The resulting basaltic landscape is significant in geography for producing fertile black “regur” soil, which is ideal for large-scale cotton cultivation.
See lessThe ‘Valley of Ten Thousand Smokes’ in Alaska is famous for which volcanic feature?
Located in Katmai National Park, Alaska, this valley was transformed by the largest volcanic eruption of the 20th century. The eruption of Novarupta buried the landscape in nearly 700 feet of hot ash. As groundwater came into contact with the heat, it turned into steam, bursting through the surfaceRead more
Located in Katmai National Park, Alaska, this valley was transformed by the largest volcanic eruption of the 20th century. The eruption of Novarupta buried the landscape in nearly 700 feet of hot ash. As groundwater came into contact with the heat, it turned into steam, bursting through the surface via thousands of fumaroles. These vents emitted gases and high-pressure steam for decades. Geographically, it represents a classic “ignimbrite” landscape. Although the “smokes” have largely diminished as the ash flow reached thermal equilibrium, the valley remains a spectacular lunar-like terrain used by scientists to understand volcanic gas emissions.
See lessWhich of the following is a ‘Positive’ landform created by intrusive volcanic activity? (A) Caldera (B) Laccolith (when exposed by erosion) (C) Crater lake (D) Ash plain
A laccolith is an intrusive igneous body that creates a distinct physical elevation, making it a "positive" landform upon exposure. It forms when viscous magma is injected into horizontal sedimentary layers but cannot spread far. Instead, it pools and pushes the overlying crust upward into a dome-liRead more
A laccolith is an intrusive igneous body that creates a distinct physical elevation, making it a “positive” landform upon exposure. It forms when viscous magma is injected into horizontal sedimentary layers but cannot spread far. Instead, it pools and pushes the overlying crust upward into a dome-like shape. In contrast, landforms like calderas are “negative” or depressional features. Once the surface layers are stripped away by millions of years of erosion, the hard volcanic rock of the laccolith remains as a topographic high. Famous examples include the Henry Mountains in Utah, which showcase these dome-shaped intrusions.
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