"To see a world in a grain of sand" is an oft-used phrase that captures some of what geologists do.
Mineral grains are smaller than a human hair.
We use the chemical processes they suggest to think about the construction of our planet.
We've taken the time to connect tiny grains to Earth's place in the universe.
Astrophysicists want to understand the universe and our place in it. The laws of physics are used to develop models of the stars.
Although we might think of the planet's surface as something shaped by processes within Earth itself, our planet has definitely felt the effects of its environment. There are variations in the Sun's output, as well as meteorite impacts.
Earth is more massive than the Moon and should remind us of that when we look at it.
The importance of meteorite impacts in the production of continental crust on Earth has been pointed out by recent work.
The rhythm in the production of this early continental crust has been identified by us and our international colleagues. The work has just been published.
There are many rocks formed from molten or semi-molten magma. The mantle is the mostly solid but slowly flowing layer below the planet's crust. When liquid magma cools, it becomes solid rock.
Through this cooling process of magma crystallization, mineral grains grow and can trap elements that decay over time and record their age.
It is possible to trap other elements that track the composition of their parents' magma, like how a surname might track a person's family.
The age and composition information can be used to reconstruct the production of crust. We can decode its main frequencies with the help of the Fourier transform.
The tool decodes the frequencies of events like unscrambling ingredients for a cake.
A 200 million-year rhythm to crust production is suggested by our results.
There is a process with the same rhythm. Our Solar System and the four spiral arms of the Milky Way are moving at different speeds as they spin around the black hole.
Our Solar System is surfing into and out of the galaxy's arms due to the fact that the spiral arms of the sun are speeding along at a rate of over 200 km per second.
The spiral arms are like dense regions that slow the passage of stars, similar to a traffic jam, which only clears further down the road.
Between the entry of the Solar System into the spiral arm of the galaxy and the model's conclusion, 200 million years have passed.
There is a possibility that there is a connection between the timing of crust production on Earth and the length of time it takes to go around the spirals.
The Oort cloud is thought to be around the Sun.
Material from the Oort cloud could be sent to the inner Solar System as the Solar System moves into a spiral arm. It is possible that some of this material may hit Earth.
The average speed of impacts from the asteroid belt is 15 km per second. On average comets arrive 52 km per second.
The record of crust production preserved in tiny mineral grains is the basis of our argument.
The impact of a comet leads to the melting of the mantle, like popping a cork on a bottle of wine.
The molten rock is rich in light elements and floats on the mantle.
It's likely that the impact on our early planet formed the seeds of continental crust. Magma produced from later geological processes would follow the seeds.
Most of Earth's natural cycles are dependent on continental crust, which interacts with water and oxygen and forms new weathered products.
Life can be wiped out by large meteorite impacts. It's possible that impacts have been key to the development of the continental crust.
Some people think that the recent passage of asteroids through the Solar System may have brought life to the universe.
It is awe-inspiring to look up at the sky and see the stars and the structure they trace, and then look down at your feet and see the mineral grains, rock, and continental crust below.
Chris and Phil are both professors of geology at the University of Lincoln.
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