Walked by a creek yesterday and realized I have no idea how water carves through solid rock

I was hiking near my town, just following this little stream, and I stopped to watch it flow around a boulder that had to be 6 feet across. It hit me that somehow, over time, that water just wears the rock down like nothing. I looked it up later and found out the Colorado River drops its riverbed by about a foot every thousand years. That rate just floored me. How does moving water beat solid stone in a fight that slow but that inevitable?

3 comments

3 Comments

kelly63823d ago

The Colorado River dropping a foot every thousand years sounds slow but Niagara Falls is actually moving upstream at like 3 feet per year because the water keeps undercutting the soft shale underneath the hard cap rock. It's wild when you think about how the Grand Canyon is basically just a really old river that refused to give up, lol. The key is that water carries tiny particles of sand and silt that act like sandpaper against the rock over millions of years, not just the water itself. That constant rubbing with sediment is what really does the damage, like using grit on a surface over and over until it wears a groove.

patricia_gonzalez23d ago

My buddy Dave actually went to the Grand Canyon last fall and he kept talking about how the water there looks so lazy and slow. He scraped his hand on a submerged rock and said the silt felt like fine glass powder, not soft mud at all. He said he finally understood why the canyon keeps getting deeper - it's literally millions of tiny scratches adding up over eons.

marywilson23d ago

I had the same kind of realization when I was picking my way along a creek bed in West Virginia a few years back. That fine sediment in the water really does feel like crushed glass under your fingers, not like mud at all. I scraped my arm on a rock and the cut was so clean it barely bled but took forever to heal. Since then I always keep a small bottle of water from wherever I'm hiking just to see how much grit is floating around in it.