Drilling to the deepest parts of the Earth as possible has led scientists to infer the Earth is about 4.6 billion years old. A period of geological time known as the Archean ( 3.5-3.4 billion years ago) has been studied through modern drilling techniques and evidence reveals climate and geological conditions at that time, regarded by geologists as the cradle for the appearance of bacterial life on Earth.
The oldest crater, 100km wide, was found in Greenland in 2012. It is around 300 billion years old and being studied now as the oldest crater, previously the oldest found was 200 billion years old. The concept of so many billions is hard for me to grasp, especially as our earliest ancestors only emerged millions of years ago.
A 6 million year old fossil found in Ethiopia is thought to be the earliest ancestor of the human race. Finding human-like fossils any older than 6 million years is very unlikely due to the ever changing nature of the skin of the Earth. But life could have been extinguished many times during the billion upon billions of years the Earth has undergone its various cyclic processes. The Earth is an integrated system with the universe, swinging out of control and back into a form of near homeostasis in a rhythmic pattern over thousands and billions of years. Maybe 6 plus million years ago we climbed out of the swamp and became what we are now. But other forms of life may have lived on this planet many times over, and been extinguished when conditions became impossible.
The British Isles was formed between 443 – 416 Millennia ago. The land which originally developed was in the southern hemisphere. It has been named Avalonia which parted from the land mass Gondwana, then collided with another land mass, Baltica, and all drifted toward Laurentia. An ice age in this period in the southern hemisphere extinguished life. When Laurentia collided with Baltica, what would become England was joined to what became Scotland. As ice sheets melted and tectonic plates shifted, the faults created the boundary between the Lowlands and Highlands of Scotland. The Southern Upland Fault and the Iapetus Suture, running from the Solway Firth to Lindisfarne, marks the close of the Iapetus Ocean and the joining of the north to the south of Britain.
The Palaeozoic era was a dramatic period of Earth development as the land masses split, reformed, moved from south to north amid great changes in climate and environment. Around 416 thousand years ago the land I stand on now travelled as the seabed of the Iapetus Ocean and was pushed up during the collision with Avalonia and Baltica to become the Southern Uplands of the Scottish Borders. The rocks which have been quarried by our cottage to be used to build a 5 mile track between South Mid Hill and Tudhope are greywacke. Well named, it is grey, dark rock with much sandstone, some quartz and feldspar interspersed. It is said to be a ‘texturally immature sedimentary rock found in the Palaeozoic strata’.
During the last Glacial Maximum (ending 12,500 years ago) most of the planet was inhospitable. It was cold and dry with frequent storms. The atmosphere was laden with dust. The sea level was lowered due to the ice sheets locking away the water. If any living thing could survive in such harsh conditions, they would have found the continental shelves above the ocean linking land masses together. Ice covered the whole of the British Isles except for a narrow band of southern England where it was a polar desert. The melting of the glaciers since that time changed the shape and contours of the land mass through water erosion to create valleys and the smooth rolling braes of the Borders. Once more habitable, humans created their own history here, albeit as dramatic as the landscape.