Drifting of Continents and Plate Tectonics

The matching shapes of coastlines on either side of the Atlantic Ocean

Step 1: The question asks about the specific meaning of 'jig-saw-fit' as used by Wegener. Step 2: Wegener observed that the coastlines of continents on either side of the Atlantic Ocean seemed to fit together like pieces of a jigsaw puzzle. Step 3: For example, the bulge of Brazil would fit into the Gulf of Guinea in Africa, and North American coastline would fit the coast of Scandinavia and Western Europe. Step 4: This similarity of coastlines, especially around the Atlantic Ocean, was termed 'jig-saw-fit' by Wegener as evidence that these continents were once joined. Step 5: The other option

Glossopteris

Step 1: The question asks specifically about a plant fossil used as evidence for continental drift. Step 2: Wegener used fossil evidence to support his theory. Among the fossils he mentioned, Glossopteris is a plant (flora) whose fossils have been found across widely separated continents like India, Australia, South Africa, South America, and Antarctica. Step 3: Mesosaurus and Lystrosaurus are animals (fauna), not plants. Step 4: Coral is a marine organism used as different evidence related to latitude and climate, not directly a plant fossil spread across Gondwanaland continents. Step 5: Ther

Polar Wandering

Step 1: The question asks about the specific term for the periodic change in the position of the magnetic pole recorded in rocks. Step 2: Certain minerals in lava and sediments (like magnetite and haematite) align themselves with Earth's magnetic field when they cool or settle. This property is retained as permanent magnetism in rocks. Step 3: When scientists study these rocks, they can track how the magnetic pole has changed position over geological time. This periodic change in the position of the magnetic pole recorded in rocks is called Polar Wandering. Step 4: Palaeomagnetism is the broad

New oceanic crust being formed at mid-oceanic ridges as plates move apart

Step 1: The question asks for the correct definition of Sea Floor Spreading. Step 2: At mid-oceanic ridges (cracks on the ocean floor), molten rock (magma) pushes up from below to form new oceanic crust. Step 3: As new crust is formed, it pushes the existing crust away from the ridge on both sides, causing the ocean basin to widen. This process is called Sea Floor Spreading. Step 4: The sinking of crust into the mantle is called Subduction - it is the opposite process. Step 5: Sliding plates past each other describes a Transform boundary, and colliding continental plates forming mountains desc