Banded iron formations studied by the authors showing the alternation between iron-rich (red) and silica-rick (white) layers. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy ...

At 2.5 billion years old and weighing in at 2.5 tonnes, the banded iron formation is so heavy that Museum engineers ... As it settled, sheets of red iron oxide were laid down between layers of ...