What is desertification?
a. method of using desert land for agriculture
b. the process of turning arable land into deserts
c. drying up of stream beds and lakes
d. the expansion of current deserts land areas

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