Throughout our series "Into the Earth," we've heard how Earth science topics cross between different disciplines like geology, physics, and chemistry. This has been true for postdoctoral research associate Steven Chemtob, whose recent research looks closely at a type of rock called banded iron formations. These rocks were created some 2.5 billion years ago, before there was oxygen in Earth's atmosphere and oceans. To understand how rocks like these formed, researchers like Chemtob have to approach the ancient formations from a variety of fields.