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Q51. Which of the following mass extinction events in geological history is associated with the conspicuous iridium anomaly?
The Cretaceous-Tertiary (K-T or K-Pg) extinction boundary layer contains a global Iridium anomaly, providing primary evidence for the asteroid impact that killed the non-avian dinosaurs.
Q52. Considering the atmosphere from the surface to 200 km altitude, the coldest region would be found around:
The coldest part of the Earth's entire atmosphere is the mesopause, located at approximately 80-90 km altitude, where temperatures can plummet to below -100 degrees Celsius.
Q53. Which one of the following currents flows equatorward?
The Benguela Current is a cold eastern boundary current flowing northward (equatorward) along the west coast of southern Africa. The others are warm western boundary currents flowing poleward.
Q54. In the asthenosphere, heat is mainly transported by:
The asthenosphere behaves as a ductile, slowly deforming solid over geological time. Heat transfer through this viscous layer occurs primarily via mantle convection, which drives plate tectonics.
Q55. Andean-type mountain belts form in:
The Andes mountains are the classic type-locality for a continental volcanic arc, formed where dense oceanic lithosphere subducts beneath a buoyant continental plate.
Q56. The severe damage in the April, 2015 earthquake in Kathmandu is caused by:
The 2015 Gorkha earthquake was a shallow, high-magnitude event (Mw 7.8) very close to the population center, causing high destruction.
Q57. Out of following, which one can be considered as the best reference point in a stratigraphic section?
Tephra (volcanic ash) is erupted and deposited almost instantaneously over massive geographical areas, making it a perfect, time-parallel marker horizon (tephrochronology) for stratigraphic correlation.
Q58. Sustainable development means:
Sustainable development is fundamentally an optimization strategy. It seeks to balance and trade-off necessary economic and social development with strict environmental protections.
Q59. Where in the ocean is the main thermocline the thickest?
Subtropical gyres centered around 30° latitude experience Ekman convergence and subsequent downwelling, which pushes the thermocline deeper and makes it thicker.
Q60. A star which is burning/fusing mostly Hydrogen is called:
Stars in the main sequence phase of their life cycle generate energy primarily by fusing hydrogen into helium in their cores.