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‘Basalt’ is a primary rock type associated with: (A) Continental crust (B) Oceanic crust and shield volcanoes (C) Fold mountains (D) Limestone caves
Geographically, basalt is the foundation of the Earth's oceanic basins. It forms at mid-oceanic ridges through the melting of the mantle. Because basaltic lava is very fluid (low viscosity), it can travel long distances, leading to the formation of broad, gently sloping shield volcanoes like those iRead more
Geographically, basalt is the foundation of the Earth’s oceanic basins. It forms at mid-oceanic ridges through the melting of the mantle. Because basaltic lava is very fluid (low viscosity), it can travel long distances, leading to the formation of broad, gently sloping shield volcanoes like those in Hawaii. Basalt is high in iron and magnesium, making it denser than the granitic rocks of the continents. This density difference is why oceanic crust sits lower than continental crust, forming the world’s ocean basins. On land, basaltic flows create fertile plains and massive “flood basalt” provinces.
See lessWhich volcanic feature is used to generate ‘Geothermal Power’ in countries like Iceland and New Zealand?
The geographical advantage of volcanic regions is the accessibility of Earth's internal heat. In countries like Iceland, New Zealand and the Philippines, subterranean steam and hot water are trapped in porous rock layers above magma chambers. By drilling production wells, this thermal energy is brouRead more
The geographical advantage of volcanic regions is the accessibility of Earth’s internal heat. In countries like Iceland, New Zealand and the Philippines, subterranean steam and hot water are trapped in porous rock layers above magma chambers. By drilling production wells, this thermal energy is brought to the surface to drive power plant turbines. After generating electricity, the cooled water is often reinjected into the ground to sustain the reservoir. This “geothermal” geography allows these nations to reduce their reliance on fossil fuels, making volcanism an essential component of their national energy security and environmental sustainability.
See lessThe term ‘Tephra’ refers to: (A) Molten lava (B) All types of airborne volcanic ejecta (ash, rocks) (C) The smell of sulfur (D) Underwater volcanoes
In volcanology, tephra encompasses all fragmental material produced by an explosive eruption. While "lava" refers to molten flow, tephra refers to the solid particles blasted into the atmosphere. Geographers study tephra layers (tephrochronology) to date prehistoric eruptions and understand the freqRead more
In volcanology, tephra encompasses all fragmental material produced by an explosive eruption. While “lava” refers to molten flow, tephra refers to the solid particles blasted into the atmosphere. Geographers study tephra layers (tephrochronology) to date prehistoric eruptions and understand the frequency of volcanic activity in a region. Fine tephra (ash) can travel thousands of miles, impacting aviation and climate, while heavier tephra falls near the vent, building up the volcanic cone. The accumulation of tephra is the primary process by which stratovolcanoes and cinder cones increase their height and geographical footprint.
See lessWhich of the following is NOT a volcanic island? (A) Iceland (B) Reunion Island (C) Maldives (D) Mauritius
Geographically, the Maldives is categorized as a coral archipelago. Unlike Iceland or Reunion Island, which are composed of basaltic volcanic rock, the islands of the Maldives are formed by the growth of coral reefs on the rim of a sunken volcanic chain. As the original volcanoes subsided or sea levRead more
Geographically, the Maldives is categorized as a coral archipelago. Unlike Iceland or Reunion Island, which are composed of basaltic volcanic rock, the islands of the Maldives are formed by the growth of coral reefs on the rim of a sunken volcanic chain. As the original volcanoes subsided or sea levels rose, the coral kept growing upward, eventually forming atolls. Therefore, the visible land surface is purely organic and sedimentary in origin. This makes the Maldives extremely low-lying and geographically distinct from the high, rugged volcanic islands found elsewhere in the Indian and Atlantic Oceans.
See lessA ‘Cinder Cone’ is built primarily from: (A) Fluid lava flows (B) Loose pyroclastic fragments (cinders) (C) Mud and water (D) Solid granite
Cinder cones are the most common type of volcano and are geographically significant for their small size and simple structure. They are built from "tephra"—specifically cinders—ejected during a single eruptive episode. As the molten lava is thrown into the air, it cools rapidly and traps gas bubblesRead more
Cinder cones are the most common type of volcano and are geographically significant for their small size and simple structure. They are built from “tephra”—specifically cinders—ejected during a single eruptive episode. As the molten lava is thrown into the air, it cools rapidly and traps gas bubbles, creating lightweight, reddish or black rocks called scoria. These fall and pile up at the “angle of repose” (about 30-35 degrees), creating the steep slopes characteristic of the cone. They are often found on the flanks of larger volcanoes or as isolated peaks in volcanic fields like Parícutin in Mexico.
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