Why fossils might be more useful than rock types in correlating rock layers on two diffrentcontinents?

Fossils can be more useful than rock types in correlating rock layers across different continents because they provide a more specific and time-sensitive record of the organisms that lived during particular geological periods. While rock types can vary widely due to local conditions, specific fossils often indicate a particular age and environment, allowing for precise correlation of layers that might otherwise appear dissimilar. Additionally, certain fossils, especially index fossils, are widespread and indicative of specific time frames, making them reliable markers for dating and correlating rock layers globally.