The Earth underwent a high number of changes from the time it was formed until now. Our planet is some 4.5 billion years old, but the rock formations and other things we see around us are much younger. Scientists know this from looking into the history of the rocks around us.
The oldest rocks in North America, located in Canada, represent some of the oldest rock formations known to mankind.
The majority of those rocks is around 2.5 billion years old. But some parts of these rocks contained traces of materials that are much older than that. In this instance the material present is neodymium-142. The fascinating thing about neodymium-142 is that it was formed in the first 500 million years of the Earth’s existence.
When scientists found these traces in rocks from 2.5 billion years ago at the center of the North American continent, they were able to conclude that those rock formations were a part of something even older. They were a part of the early ocean floor which dates back some 4.3 billion years.
These findings raise even more questions about the Earth’s first couple of billion years. What happened between the period when that area was submerged and the period when it formed the continent we now know as North America?
Currently, Earth’s landscape is dictated by plate tectonics. The shifting of the continents and oceans around Earth’s molten core forms everything we see around us today. That was not the case during the Earth’s first couple of billion years.
As the continents shift new oceanic crusts are formed. Over the next 200 million years these crusts shift around until they are thrust beneath those same continents that helped create them. Unlike these newly formed crusts, early oceanic rocks were able to survive for a billion years, which clearly indicates that something different was occurring on Earth’s surface.
All these findings indicate that the Earth might have had a single outer layer which did not have as many cracks as today’s crust has.
Rocks that were recently found in another craton in Australia point to those exact same findings.
Scientists still have a lot to learn about the Earth’s early years. Traces of a previous Earth are still out there and are just waiting to be found. New tracers for finding those traces have only been discovered in the last 12 years. They need to be applied in other places on our planet in order for us the gain a clearer picture about Earth’s past.