Answer: D. It can melt to a depth of a few meters in summer, then refreeze in winter.
Explanation:
Permafrost is ground which remains frozen for two or more years. Permafrost consists of soil, rock and sand fused together by ice. Mostly found in areas in high altitude, the Arctic, Antarctica, it is common in periglacial environments where temperatures are below freezing
.
The topmost layer of permafrost can melt in summer and refreeze in winter. This thawing and refreezing produces a ground pattern called columnar joints similar to the one formed when molten lava cools.
Answer: Africa includes the rich source of water drainage in the form of rivers.
Explanation:
The course travelled by the major rivers in Africa are as follows:
1. Congo: Center to north and further to the Western region finally drains into the Atlantic Ocean.
2. Nile: Northeastern part to the North and then finally to the Mediterranean Sea.
3. Zambezi: South eastern to Indian Ocean.
4. Niger: West to the Guinea Gulf.
