How is it possible for dinosaur footprints that are hundreds of millions of years old to exist at the bottom of a riverbed without being eroded away by the water?

Question

Many parts of Texas are experiencing severe drought (though not quite as severe as the b*tch that was the 2011 drought). As a result of these exceptionally dry conditions, a certain riverbed in Dinosaur Valley State Park has run dry, exposing previously undiscovered dinosaur tracks that are roughly 113 million years old. How is this possible—like, how have they not been eroded by the river? Water is pretty excellent at eroding rock, especially over the course of 113 million years. On the one hand, I do understand that most likely the river has not been there as long as the dinosaur tracks have been, but on the other hand (1) we actually don’t know this for sure, and (2) even if it has been there for less time than the tracks have been, there certainly has still been ample time to erode them away. What am I missing here?

[https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjWsazb4t_5AhXRk2oFHVUIBawQvOMEKAB6BAgGEAE&url=https%3A%2F%2Fwww.cnn.com%2F2022%2F08%2F23%2Fus%2Fdinosaur-tracks-discovered-texas-park%2Findex.html&usg=AOvVaw2co9awHFuiD-qAeMOP5DNk](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjWsazb4t_5AhXRk2oFHVUIBawQvOMEKAB6BAgGEAE&url=https%3A%2F%2Fwww.cnn.com%2F2022%2F08%2F23%2Fus%2Fdinosaur-tracks-discovered-texas-park%2Findex.html&usg=AOvVaw2co9awHFuiD-qAeMOP5DNk)

*EDIT/UPDATE: Aha! It now makes sense. It turns out that these particular dinosaur tracks were first discovered in 1908, when a layer of rock that had been covering the tracks broke up and washed away due to a flood. In the time since then, there have been multiple paleontological excavations that have revealed even more of the tracks. And the most important thing to know here—the thing that ties it all together and makes everything “click”—the River* ***has*** *been eroding the prints ever since the first tracks got exposed in 1908. It’s just that obviously on a geological timescale, the 114 years between 1908 and now are just a tiny, minuscule blip in the grand scheme of things… nowhere near long enough for the tracks to have been eroded. So it all makes sense, knowing that the river has only been eroding the tracks for 114 years instead of 113 million years.*

*Source:* [*https://www.nps.gov/…/nature/making-dino-prints.htm…*](https://www.nps.gov/dena/learn/nature/making-dino-prints.htm?fbclid=IwAR3MZ-SQHiJg8uZ7LEjeSZTNgE705yDE4x54VFmrHZgGdySHhI5kLdXgcO4#:~:text=When%20dinosaurs%20walked%20through%20the,where%20people%20can%20see%20them)

In: 1541

Answer 1

Fluid flow dynamics where fluid wall velocity equals zero. So, a unless an obstacle is in the path of the fluid like the bottom of a river bed, minimal erosion will occur.