The Earth wasn't always a friendly place to live. Not only was it covered in lava and constantly eruption, its atmosphere was chocked with volcanic gases like carbon dioxide and sulfur dioxide. How and when did the atmosphere reach its current oxygen-rich state? This post will walk through the processes as well as some of the evidence that allows us to understand what happened. While I describe as a series of apparently discrete steps, it's important to remember that these processes sometimes overlapped and that they occurred over a span of time, often millions or billions of years.
Easy Science: The Great Oxygenation Event
How zircons help us date and understand the ancient earth
Small and unimposing at just fractions of a millimeter across, the igneous silicate mineral zircon (ZrSiO4) lays its claim to fame as the oldest earth material at 4.4 billion years old. The secret to zircon's success is its durability and tenacity. When other minerals break apart or turn into other minerals, zircon bravely trudges on. My former professor, Dr. Alex Glass of Duke University, described zircon as "the thing that never leaves," comparing zircon to a person who awkwardly remains at a house party long after all the other guests have left. He suggested that rather than diamonds, zircons should be the ultimate symbol of everlasting love. Read more →
Easy Science: simple timeline of pre-Cambrian earth and life
Understanding the formation of the earth can be overwhelming. I've simplified and condensed the big events into an easy-to-follow timeline. Obviously, the list is not meant to be exhaustive and probably isn't 100% accurate. Clicking on the links will take you to Wikipedia that lead to journal articles (a few links directly to sources). Read more →