Oldest Earth fragment is 4.4 billion years old

By Casey Frye, CCNN Writer

Earth's crust
A theoretical timeline of Earth’s crust formation – including the crystal – and the evolution of life.

According to modern science, our Earth formed around 4.6 billion years ago. Before it was the blue, life-giving planet we see today, it was a fiery inferno of lava. Because of this, scientists have long suspected that the Earth’s crust didn’t form until much later, but after discovering a 4.4-billion-year-old crystal, they’re rethinking that theory.

Researchers have now concluded that our crust formed shortly after our planet’s birth, and there may have even been liquid water.

See, the crystal is a type of zircon – an ancient grain material that provides the only physical evidence left from Earth’s early days. Though our planet is said to be 4.6 billion years old, the earliest fossils (ancient animal bones) only date back to 3.5 billion years. This leaves a huge mysterious gap in those first 200-300 million years where life may have thrived. By carefully studying the elements called lead and uranium inside of the zircon, researchers have determined Earth had some form of solid crust around 4.4 billion years ago. Additionally, the oxygen present inside the tough crystal suggests that our planet had some liquid water trickling along its surface.

Since Earth had both liquid water and a solid crust about 100 million years after forming, ripe and ready for life to take form, scientists are having to reconsider a great many theories.

Featured image courtesy of John Valley. Image of timeline courtesy of University of Wisconsin – Madison.