Earth’s Crust and the Milky Way

In attempting to explain earthly phenomena, geologists tend to look downward at Earth itself. It now appears they need to shi‚ their gaze skyward.

Per a paper in the journal Geology, an international team led by isotope geologist Chris Kirkland (Curtin University, Australia) examined zircon crystals contained within ancient continental crust from samples gathered in Australia and Greenland. How ancient? Between 2.8 and 3.8 billion years old. ey discerned that during this period, crustal production increased in a cycle of every 200 million years. at coincides with the passing of our solar system through the dense spiral arms of the Milky Way.

eories and potential explanations abound to explain the rate of crustal production. e one favored by Kirkland’s team? Just perhaps, during those cycles of our solar system moving through space, more comets rain down, causing more magma to rise here on Earth. e comets would have been dislodged from the Oort cloud because of the density of the spiral arms.

What really drives things here on Earth? Internal forces of geology or galactic forces far beyond Mother Earth’s control?