[Mission 2022] QUIZ – 2020: INSIGHTS STATIC QUIZ , 14 October 2021 – Geography – INSIGHTSIAS

Solution: d)

The Earth’s geomagnetic field is a combination of several magnetic fields generated by various sources superimposing on each other. More than 90% of the field is generated by the movement of conducting material inside the Earth’s core, which is often referred to as the Main Field. Other important sources of the geomagnetic field include electric current flowing in the ionized upper atmosphere and currents flowing within the earth’s crust. There are also local anomalies produced by mountain ranges, ore deposits, geological faults, and artificial products such as trains, aircraft, power lines etc.

Solution: d)

All of the above will bring dynamic changes on the earth.

Solution: b)

Magnetic response of rocks is determined by amounts and susceptibilities of constituent minerals. Most Sedimentary rocks have very low susceptibility to magnetic field of earth. So, there is little alignment in their constituents in response to earth’s magnetic field. For ultramafic rocks it is the highest.

Foliation refers to repetitive layering in metamorphic rocks. When the pressure is greater in one direction than in the others (directed pressure), it causes the minerals in the original rock to reorient themselves with the long and flat minerals aligning perpendicular to the greatest pressure direction. This reduces the overall pressure on the rock and gives it a stripped look.

Solution: b)

Oceanic crust is the result of erupted mantle material originating from below the plate, cooled and in most instances, modified chemically by seawater.

It is primarily composed of iron and magnesium. It is thinner than continental crust; however it is denser.

Solution: b)

Mid-ocean ridges are geologically important because they occur along divergent plate boundaries, where new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate, some molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt, and building the longest chain of volcanoes in the world. Because most of these eruptions occur deep under the water, they often go unnoticed.