What are some open-ended questions about Earth's history or geology?

Question

An open-ended question is something that can be explored and doesn't have a certified answer already.

An example of what I'm looking for is: How does Earth change over time?

Answer 1

How does the composition of Earth compare to that of other planets in our solar system?

What does the theory of plate tectonics imply about continental positions a billion years from now?

Why do volcanoes and earthquakes often occur in the same areas?