What unit of time on earth is based on the revolution of the moon around earth?

According ti the following map, what are the most common mineral resources found in the united states?

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

Geographers most often use this type of map to study the characteristics of regions such as population and naturalresources because blank spaces are put into the map to prevent distortion.feelperfet