Iron-rich hills in Australia hold the oldest piece of Earth's crust we have found yet. Earth is thought by scientists to have been formed around 4.5 billion years ago, and zircon crystals in the rocks were dated to 4.4 billion years old by radioactive dating back in 2001. Recently, scientists shaved off pieces of the zircon crystals, and found radioactive lead atoms inside that were trapped in lava as it solidified (the lead used to be uranium but decayed into lead). They were able to more accurately date the crystals to 4.374 billion years old (plus or minus 6 million years).
This article states two facts that I think are pretty amazing:
-the rocks formed about 160 million years after our solar system formed; and
-the rocks formed when an object the size of Mars hit Earth and created the Moon. This formed a world-wide lava ocean which cooled to form the early Earth's crust!
http://news.nationalgeographic.com/news/2014/02/140224-oldest-crust-australia-zircon-science/
This article states two facts that I think are pretty amazing:
-the rocks formed about 160 million years after our solar system formed; and
-the rocks formed when an object the size of Mars hit Earth and created the Moon. This formed a world-wide lava ocean which cooled to form the early Earth's crust!
http://news.nationalgeographic.com/news/2014/02/140224-oldest-crust-australia-zircon-science/