"To see a world in a grain of sand," the opening sentence of the poem by William Blake, is an oft-used phrase that also captures some of what geologists do.
We observe the composition of mineral grains, smaller than the width of a human hair. Then, we extrapolate the chemical processes they suggest to ponder the construction of our planet itself.
Now, we've taken that minute attention to new heights, connecting tiny grains to Earth's place in the galactic environment.
Looking out to the universe
At an even larger scale, astrophysicists seek to understand the universe and our place in it. They use laws of physics to develop models that describe the orbits of astronomical objects.
Although we may think of the planet's surface as something shaped by processes entirely within Earth itself, our planet has undoubtedly felt the effects of its cosmic environment. This includes periodic changes in Earth's orbit, variations in the sun's output, gamma ray bursts, and of course meteorite impacts.
Just looking at the Moon and its pockmarked surface should remind us of that, given Earth is more than 80 times more massive than its gray satellite. In fact, recent work has pointed to the importance of meteorite impacts in the production of continental crust on Earth, helping to form buoyant "seeds" that floated on the outermost layer of our planet in its youth.
We and our international team of colleagues have now identified a rhythm in the production of this early continental crust, and the tempo points to a truly grand driving mechanism. This work has just been published in the journal Geology. READ MORE...
