Which challenge does canada face in its effort to reduce the use of fossil fuels

The point where two air masses meet is called a

During which era in earth's history were the first insects? mesozoic precambrian cenozoic paleozoic

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