Convection occurs in fluids (so both liquids and gases, as well as rheids) and is the concerted, collective movement of groups or aggregates of molecules within the above through advection or diffusion or both at the same time. Convection can never take place in solids and is only specific to fluids.
Gold is plentiful in Africa and is a necessity for most technological devices.
It really depends on which war the question is referring to, but if it's referring to WWII the answer would be true.
i. Using fossil evidences
ii. Similar rock lithologies at the edges of continent
iii. Climate clues
iv. Fitting of the continents into a puzzle
v. Sea floor spreading
Explanation:
Pangea was a super-continent on the earth which formed about 330 million years ago during the Paleozoic and began breaking up during the early Mesozoic, about 175 million years ago.
Most of the present day continents formed as a result of the separation of the Pangea in the early Mesozoic.
The first scientist to propose the existence of this super-continent was Alfred Wegener in 1912. He suggested the continental drift hypothesis to explain the separation of the land masses.
Today, the theory has been revised to the theory of plate tectonics which provides a better mechanism to understand the drifting of the continents.
Here are some of the evidences to support the existence of Pangea;
- Using fossil evidences: Mesosaurus, a reptile animal that lived during the Permian, was found in both South America and Southern Africa. Since this animal could not swim nor fly, only a jointed landmass could have made them present in both continents.
- Similar rock lithologies at the edges of continents: rock formations at the Western edge of Africa and South - Eastern part of Brazil matches with one another and have been believed to be once joined together.
- Climatic clues such as glacial tills that are confined to temperate and polar regions have been found in tropical regions.
- Wegener fitted the present day continent into a giant supercontinent and this provided a visual support for his claim.
- Evidences from sea floor spreading revealing magnetic reversals at divergent margins suggests the prevalence of plate tectonics i.e moving plates on earth.
This among many other evidences underscores the existence of a supercontinent called Pangea.
The answer is b. elastic deformation
In geologically active areas, stress causes rocks to deform or stretch out. But when the stress ends, the faults return back to normal through elastic deformation. They regain their original shape.
