When looking at a geological timescale, typically ‘the deeper you dig, the older stuff gets’, right?
So, where does this buildup of new sediment come from?
I understand we’re talking about very large timeframes here, but I still dont really get it.
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On land, you can easily see dirt forming around you. It’s the natural remnants of a crumbling world: trees decay, drop leaves, animals poop, living things die, rocks erode and turn to dust …all this matter becomes dirt. Now imagine a new volcanic rocky outcrop emerging from the ocean. It’s barren. But over time, life happens: seabirds poop on it. Lichen spores blow in on the breeze, settle down, begin growing on the rock, and eating into it. They emit acid which helps break down the rock a litttle, but also hold onto dust in the air, and trap it, accumulating it. Rainfall and wind helps grind down the rock. In just a few years, a barren rocky island in the middle of the ocean begins to form dirt on top, and soon offers a home to seaborne seeds which happenstance washes ashore, to become the pioneers of a future forest.
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