There were no geologists alive when the Bright Angel shale layer formed. However, scientists have been able to determine that this rock formed near the shore of an ocean. What evidence could geologist

There were no geologists alive when the Bright Angel shale layer formed. However, scientists have been able to determine that this rock formed near the shore of an ocean. What evidence could geologists use today to find out about this ancient rock layer? Enter your answer in the space provided.