What are the answers for the following questions?

Explain how a convection current in the earth is formed.

Many areas surrounding the caspian sea contain important a. rare minerals b. forestry resources c. gold and silver mines d. oil and natural gas fields

Why is the huronian supergroup rock formation particularly interesting to scientists? because it looks like a cross-section of a giant, stone encyclopedia because it formed during the period when oxygen began to accumulate in the atmosphere because it contains unusually large amounts of oxygen and sulfur because it dramatically altered the planet's development when it first formed