Very little arrives {those asteroid impacts are few and far between}, and only a whisper of gas escapes. Everything else must be endlessly recycled: and so it is. The rain becomes the ocean and the ocean becomes the rain, the mountains are ground down to cover the sea-floors with silt, ancient silts rise up to make new mountains.
The process of Earth's material cycling is slow and vast, marked by the infrequent asteroid impacts that bring new elements. These rare events contribute minimal gas to the atmosphere, emphasizing the necessity of recycling existing resources. Nature continuously transforms—rain feeds oceans, and ocean waters evaporate to form rain again, showcasing a closed cycle of water.
This dynamic also applies to landforms; mountains erode and their sediments become part of the sea floor, while older layers surface over time to create new elevations. Bryson illustrates the interconnectedness of Earth's systems and the significance of material recycling in maintaining the planet's ecological balance.
