Post-drift studies and Convectional Current Theory

Correct answer: A. Internal heat can create slow currents in the mantle

The scientific basis of the theory lies in heat and slow movement of mantle material. Exam tip: avoid overly simple external causes.

Correct answer: A. Because they provided supporting indications of possible plate movement

Wegener's evidence remained useful, but it needed a better mechanism. Exam tip: understand the difference between evidence and mechanism.

Correct answer: B. Rising current and divergent boundary

A rising current creates spreading, which forms a divergent boundary. Exam tip: remember rise, spread, and separation together.

Correct answer: B. It did not fully explain the geometry and processes of plate boundaries

Holmes gave a driving idea, but the detailed plate-boundary model developed later. Exam tip: distinguish precursor from complete theory.

Correct answer: A. Rising current can form new crust and move it sideways

Rising material at ridge zones is linked with new crust and spreading. Exam tip: see spreading as a surface result of convection.

Correct answer: B. Slow but organized material movement will be possible

The direct answer is B: slow but organized material movement will be possible. Convection is movement caused by differences in temperature and density. Step by step: heat is unevenly distributed in the mantle; warmer material becomes less dense and tends to rise; cooler material becomes denser and tends to sink; this rising and sinking can form convection cells; the movement is gradual and organized rather than an instant, uncontrolled event. Such movement was proposed as a mechanism that could help explain large-scale motions connected with continental drift, although modern plate tectonics gives the fuller explanation. Option A is wrong because mantle convection does not stop Earth’s rotation. Option B is correct because it describes the expected slow circulation of mantle material. Option C is wrong because mantle heat does not make all oceans dry up. Option D is wrong because the theory concerns movement inside Earth, not only atmospheric storms. Memory cue: unequal heat produces rise, sink and circulation.

Correct answer: A. Because plates may include both continental and oceanic crust

In modern understanding, plates are lithospheric units. Exam tip: do not treat continents and plates as identical.

Correct answer: B. Convection cell

Rising, lateral flow, and sinking together form a convection cell. Exam tip: understand the complete circulation of the cell.

Correct answer: C. Magnetic anomalies of the ocean floor

Detailed study of magnetic anomalies later became major evidence for seafloor spreading. Exam tip: separate older and newer evidence.

Correct answer: C. By slow movement of mantle material

Slow movement of mantle material can exert drag on the overlying crust. Exam tip: identify the medium as mantle, not air or water.

Correct answer: B. Where descending current and convergence are active

Convergence and sinking are linked with oceanic trenches. Exam tip: connect trenches with plate sinking.

Correct answer: A. Many of his evidences were in the right direction but the driving force was weak

Wegener gave evidence for movement, but the mechanism was insufficient. Exam tip: write a balanced criticism of the theory.

Correct answer: B. Descending current and subduction

Old dense oceanic crust can sink at convergent zones. Exam tip: connect density with subduction.

Correct answer: A. Slow cyclic flow of material below the surface

Cyclic flow beneath the surface can create movement and stress in the crust. Exam tip: link dynamic Earth with internal processes.

Correct answer: B. Slow long-term speed

Geological processes create large changes slowly over very long periods. Exam tip: remember geological time scale.

Correct answer: A. Because together they explain the balance of creation and destruction of oceanic crust

Crust is created at ridges and destroyed at trenches. Exam tip: write the balance of creation and destruction.

Correct answer: A. It discusses heat-driven material movement inside Earth

The theory explains the internal process behind surface changes. Exam tip: distinguish description from process.

Correct answer: A. Rigid plates can move over a relatively weaker layer

Movement of lithospheric plates over the asthenosphere became a basis of plate tectonics. Exam tip: remember the role of layers.

Correct answer: A. Lateral flow of the mantle

Lateral mantle flow can create drag at the base of the crust. Exam tip: link basal drag with mantle flow.

Correct answer: A. It shifted the debate from mere speculation to evidence-based analysis

Ocean-floor mapping and magnetic studies provided new evidence. Exam tip: understand the relation between technology and evidence.

Correct answer: A. New crust forming at the ridge and becoming older away from it

Crust farther from the ridge has more time to collect sediments, so thickness may increase. Exam tip: link sediment thickness with age.

Correct answer: A. Tensional stress caused by rising and spreading current

Spreading creates tensional stress and may fracture the crust. Exam tip: connect tension with divergence.

Correct answer: B. Plate tectonic theory

Plate tectonics explained both continental and oceanic plate movements. Exam tip: see drift as part of the broader plate theory.

Correct answer: C. It gives a possible internal mechanism for continental movement, but modern plate tectonics explains it more clearly

Convection theory was an important step, but the full modern explanation lies in plate tectonics. Exam tip: a balanced conclusion is safest.

Correct answer: A. It shows the possibility of slow movement beneath rigid lithospheric plates

The plastic nature of the asthenosphere makes material movement beneath plates possible. Exam tip: remember the difference between lithosphere and asthenosphere.