B. The various climate zones support biodiversity
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.
Scientists<span> can tell by observing the seismic waves that are recorded all over the surface of the </span>earth<span> from distant earthquakes. The seismic waves are reflected (bounced off) </span>layers<span> of different density, and they are refracted (bent) when they enter </span>layers<span> of different density.</span>
