Earth's Carbon Concentrations (image) Deep Carbon Observatory Caption While we know approximately the thickness of Earth's layers, the quantities of carbon below the surface in each layer remain a mystery. Even estimates of carbon in the crust are uncertain. Fluxes between the layers complicate the mystery and the quest of the Deep Carbon Observatory. Credit Deep Carbon Observatory Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.