Post-drift studies and Convectional Current Theory

Later studies linked ocean floor and mantle with continental movement. Exam tip: write both new evidence and mechanism.

Holmes gave a way to explain Wegener's weakness of driving force. Exam tip: link Holmes with mantle convection.

Slow mantle movement can exert force on plates above it. Exam tip: understand the position relation of mantle and plates.

Mapping revealed ridges trenches and submarine mountain chains. Exam tip: do not treat the ocean floor as an inactive plain.

Ridge zones are linked with formation of new material and spreading on both sides. Exam tip: write ridges as formation zones.

Trench zones may be linked with sinking and subduction. Exam tip: connect trenches with downward movement.

Seafloor spreading helped in treating Earth's surface as dynamic. Exam tip: consider it later support.

Study of age with distance from ridges explains seafloor spreading. Exam tip: remember the age-ridge relation.

Heat from radioactive decay can provide energy for convection. Exam tip: treat internal heat as the main source.

Earthquakes and volcanoes are related to active boundaries of Earth. Exam tip: connect distribution with plate boundaries.

A convection cell shows continuous cyclic movement of material. Exam tip: understand a cell as a cycle.

Ridges and trenches showed complexity and activity of the ocean floor. Exam tip: understand ocean floor as a dynamic structure.

The direct answer is option A: post-drift studies included the ocean floor and mantle processes along with continental movement. Wegener mainly explained that continents had once been joined and later moved apart, but his original explanation did not fully establish the driving mechanism. Later research examined mid-ocean ridges, trenches, seafloor spreading, mantle convection and plate movement. Therefore the explanation expanded from moving continents alone to a connected Earth system involving continents, oceans and the interior. Option A is correct because it states this broader development. Option B is wrong because later studies did not deny continents. Option C is wrong because oceans became highly important evidence, not irrelevant. Option D is wrong because geography is not limited to weather and these studies concern Earth structure and movement. Exam cue: Wegener gave the continental-drift idea; later evidence supplied a wider mechanism.

Upwelling material at ridges is linked with new ocean floor and spreading. Exam tip: study spreading and upwelling together.

Magnetic stripes are important later palaeomagnetic evidence. Exam tip: do not treat them as Wegener's original proof.

Palaeomagnetism later became important for supporting plate movement. Exam tip: keep chronology in mind.

Mantle may seem solid but can behave like flow over long time. Exam tip: remember the time scale.

New floor spreading on both sides of a ridge indicates seafloor spreading. Exam tip: treat ridge as spreading center.

Deep trenches and earthquakes can indicate an active subduction zone. Exam tip: connect trench earthquakes and plate boundary.

Oceanic evidences expanded the explanation of movement beyond continents. Exam tip: write the importance of ocean floor.

Direct answer: A. In the convectional current theory, heat differences inside the Earth produce movement in mantle material. When heated material becomes less dense, it rises; when it cools and becomes denser, it sinks. Rising currents can push material apart and produce spreading, while descending currents can pull material downward and produce sinking or convergence. Thus both movements are possible because currents rise in some places and descend in others. Option A correctly describes this two-way circulation. Option B is wrong because equal rainfall is a weather process and does not create mantle convection. Option C is wrong because river flow is surface drainage, not the cause of tectonic convection. Option D is wrong because mountains do not always melt, and melting is not the explanation for the circulation. Memory cue: hot and light rises; cool and heavy sinks. The supplied answer is scientifically suitable for the school-level theory.

The direct answer is A: Holmes added a possible force or mechanism that could explain continental movement. Wegener presented evidence that continents had once been joined and later drifted, but his original explanation of the driving force was not convincing enough. Arthur Holmes proposed that convection currents inside the mantle could help move the crustal plates. Step by step: Wegener supplied the movement idea and supporting evidence; a theory also needs a mechanism; Holmes suggested heat-driven convection as a possible mechanism; this made his idea complementary to Wegener’s, not a denial of it. Option A is correct. B is wrong because Holmes did not say all continents were permanently fixed. C is wrong because later explanations did not deny fossil evidence. D is wrong because oceans were not removed from the theory. Memory cue: Wegener explained what happened; Holmes helped explain how movement might happen.

Post-drift studies are linked with better scientific explanation of continental movement. Exam tip: remember evidence and mechanism.

New oceanic crust forms at the ridge and moves outward. In exams, treat the age pattern as key evidence of spreading.

Symmetrical magnetic stripes show that new rocks spread on both sides at comparable rates. In exams, cite this as strong evidence of sea-floor spreading.