Why are ancient volcanic ash deposits important to geologists? a. They form resistant rock layers containing fossils.
b. They are easily dated using carbon-14.
c. They serve as good geological time makers.
d. They indicate major areas where earthquakes occurred.

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