The Archaic period started about 4.5 billion years ago and ended about 2.5 billion years ago. It was in this era that our planet came into being. When the earth was created, so much energy was radiated that the elements that made up the earth melted. In this boiling mixture, the heavier elements sank to the earth’s core. That is why nowadays the earth’s core mainly consists of iron and nickel, and the earth’s crust of silicon and oxides. The earth’s crust is so unique, it cannot be found anywhere else within our solar system, not even in the planets which otherwise have much in common with the earth, such as Mars, Venus and Mercury.
Since the previously mentioned geological processes took place many many years ago, not very much is known about them. By comparing planet earth with our moon and other planets, it is hypothesised that between 600 and 700 million years after the birth of our solar system, the planets between the sun and the earth were bombarded with material from the sun. Despite these fierce bombardments, very few craters on the earth’s surface are visible today. The difference between the earth and the other planets is that all kinds of geological processes have erased the comets’ impacts. Because of all these impacts during the earth’s history, our planet would have about 3000 craters with a diameter of more than 100 km each.
These direct hits had some major consequences. Firstly, the total amount of material within the earth increased. Secondly, the variety of elements increased, and thirdly, the ‘heavy’ elements (that had sunk to the earth’s core) were shaken up and distributed more randomly throughout the earth’s crust. On both the earth and the moon are very very few any rocks older than 3.9 billion years old. With all these impacts, it was impossible for rocks to form. An exception are zirconium minerals from Australia, which are between 4.3 and 4.2 billion years old.
Sea water: 70 degrees Celsius
From very old rocks found in Antarctica and Greenland, it can be deduced that water was present about 3.8 billion years ago. From the total surface area of the earth, only between five and ten percent was mainland; the other ninety to ninety-five percent was oceanic crust. The temperature of the sea was an amazing 70 degrees Celsius – far too hot to swim in. The crust was constantly moving: earth quakes and volcanic eruptions were the order of the day. About 3 billion years ago, this picture changed somewhat. Between 2,800 and 2,500 million years ago, the earth’s crust increased in size. From the crust that we know today, more than half of it was already present at the end of the Archaic period.
It is a fact that 3.5 billion years ago there was life on this planet. Stones of 3.8 billion years old demonstrate the existence of stromateolites (micro-organisms that formed structures with the help of sediment). These stromateolites played an important role in the development of the atmosphere, since their photosynthesis caused an increase in the amount of oxygen in the air. Photosynthesis is the process in living plants.