What minerals gave way to the development of trade networks in Africa?

Renewable resources of west and central africa include:

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

Which descriptions refer to cirrus clouds? check all that apply. are fluffy are wispy produce snow form at high altitudes form from ice crystals