The oldest rock
Ancient rocks appear in the crystalline basement inside the continent. Representative rocks are basic and ultrabasic igneous rocks. These rocks have been transformed into metamorphic rocks rich in chlorite and amphibole due to strong metamorphism, which we usually call greenstone. For example, in 1973, a granitic gneiss with an isotopic age of about 3.8 billion years was discovered in West Greenland. In 1979, Bayu et al. determined that gneiss in the middle of the Bobolin belt in South Africa was about 3.9 billion years old. The metamorphic rock in the north of Canada - the Akas card gneiss is part of the well-preserved ancient earth's surface. The radiological dating has shown that the Akas card gneiss has an age of nearly 4 billion years, indicating that certain continental materials have existed hundreds of millions of years after the formation of the Earth. Recently, scientists have discovered a group of the oldest rocks in southwestern Australia. According to the isotope analysis of the zircon mineral crystals contained in them, they have shown that their "age" is about 4.3 to 4.4 billion years old. The oldest rock samples, based on this finding, can be inferred that when these rocks were formed, there were already continents and oceans on Earth. After 200 to 300 million years of birth, the Earth may not be covered by hot magma as it is believed, but it has cooled to a temperature sufficient to form a solid surface and ocean. The earth's layer of differentiation may have been completed 4.4 billion years ago. The oldest rock found in China is the granitic gneiss in the eastern part of the country, where the age of the inclusions is about 3.5 billion years. Suzhou Newstar Hardware Co.,Ltd. is committing to Hand Tool Kits for more than 10 years, now is China good manufacturer and supplier of Hand Tools kits, han tools kit, Hand Tool Set. And we are specialized in Hand Tools Kit Bag, Hand Tool Trolley, Hand Tool Cabinet etc. We are very strong in OEM and ODM services based on customer needs, with customer logo and design. Hand Tools Kits,Hand Tools Kit,Hand Tools Kit Bag,Hand Tool Kits SUZHOU NEWSTAR HARDWARE CO.,LTD. , https://www.hardwarenewstar.com