Oceans 4.4 Ga
One small crystal from Western Australia indicates the presence of an ocean very early in Earth history. And where there’s water there may be life.
Why It Matters
- One zircon grain is the oldest material we have that found on Earth.
- The grain is formed 4.4 billion years ago (Ga or giga annum), only 150-million to 300-million years after the planet.
- During the Hadean, meteorite bombardment kept much of Earth’s surface molten.
- The zircon formed at about 680° C, which indicates the presence of water.
- The zircon may have formed in rocks that melted at a subduction zone.
With the links below, learn more about the oldest zircon. Then answer the following questions.
- NPR, krulwich wonders, The Oldest Rock in the World Tells Us a Story: http://www.npr.org/blogs/krulwich/2013/01/10/169047159/the-oldest-rock-in-the-world-tells-us-a-story
- NASA, Earth Observatory, Ancient Crystals Suggest Earlier Ocean: http://earthobservatory.nasa.gov/Features/Zircon/
- Why is the oldest material a zircon grain?
- Why don’t we have rocks that old?
- How does the titanium thermometer work?
- Why does the 680o C formation temperature for the zircon indicate the presence of water?
- Why is the early presence of an ocean so exciting to scientists?