When I was researching the ancient Earth, I came across some stories about the earliest geological era. The period 4.6 to 4 billion years ago after the birth of the Earth is called the Hadean Era, which is apparently when the crust and oceans were born, but not much geological evidence has been found about it. It seems that it was named Hadean as a metaphor for the fact that there is much we don’t know about it and it is shrouded in darkness. All of the few traces of the Hadean Era that have been found so far are said to be the oldest.
https://www.hadean.jp/about/about_index.html
The oldest rock is a metamorphic rock called granitic gneiss found in Acasta in northern Canada, estimated to be 4.02 billion years old. Gneiss is a rock formed when granite is metamorphosed at high temperature and pressure deep underground, and the oldest rock in Japan is also granitic gneiss, estimated to be 2 billion years old. Gneiss is a rock that is durable and easily preserved, making it easy to determine its age.
https://news.yahoo.co.jp/articles/70f2a07a8c4e841e3e11b9d5845963998b5d9f03?page=3
The oldest known crust is a rock found in the Hudson region of Canada, which is estimated to have separated from the mantle 4.2 billion years ago. The rocks that cover the Hudson Bay area are the only part of the crust that exists from the Hadean Era. It’s possible that the oldest rocks and the oldest crust were found in close proximity to each other in northern Canada, but it’s amazing that such ancient traces still remain today.
https://natgeo.nikkeibp.co.jp/nng/article/news/14/422
The oldest mineral is zircon, found in the Jack Hill region of Western Australia, estimated to be 4.4 billion years old. Zircon is a silicate mineral of zirconium, and is a gemstone with a brilliance similar to that of diamonds. Zircon is found in granite and other rocks, and is more resistant to weathering and metamorphism than minerals such as quartz and feldspar. It contains uranium-238, which has a half-life of 4.47 billion years. Uranium-238 is an element with a very long half-life, and the amount of uranium-238 that existed when the Earth was born has only recently been reduced to half.
http://www.ha.shotoku.ac.jp/~kawa/KYO/DEM2/weh/zircon/index.html
I looked into the traces of the Hadean dynasty, and I feel that the word “oldest” is very precious. It is amazing that there are things on Earth that have remained unchanged since its birth, even though the Earth has been constantly changing. The Hadean dynasty and its traces are amazing. The age of the Earth is amazing.
