The Fascinating Rocks of Horsemen's Center

For this learning outcome, I went hiking in Horsemen's Center Park in Apple Valley. It's a pretty special place to me, as I've gone there with my family more times than I can count. But since taking this class and visiting the park again, I've been able to appreciate its landscape and the processes behind it even more.

The rock structures of Horsemen's Center are what make the area so memorable to me. So how did they form? The rocks here are intrusive igneous rocks (primarily monzogranite) meaning that they formed from rising molten material and cooled below the surface. Due to pressure, water, and eventually surface erosion, these rocks were shaped into what can be see today. For more on these kinds of formations, check out this link.

The vast majority of the rocks appeared to have varying degrees of reddish or black external coloration, called desert varnish. While this isn't a weathering process, particles of iron, manganese, and clay are all a part of its formation. Colonies of bacteria and fungi also play a role, which I find really interesting.

This large rock seems to be an example of exfoliation. Its surface is flaky, as if small layers of the rock were shed. This was caused by the release of pressure as the rock was uplifted.

A lot of the rocks on the ground showed signs of what may be some form of thermal stress. Similar to exfoliation, it is a form of mechanical weathering caused by changes in temperature. The rock expands with heat and contracts with cold temperatures, and as this happens over and over again, the structure of the rock weakens.

Interestingly, the area right next to the one shown above features flatter and darker rocks on the ground. I find it cool that such close areas can look so differently from each other!

One of my favorite individual rocks that I found on the hike is what I call the "dog head" rock. Doesn't it look like the side profile of a dog? It's interesting how the left side (or the "snout") doesn't have anything beneath it for support, and yet it still stays upright! It makes me wonder, at what point did it become this way? Was it mainly eroded below the surface and uplifted, or was it the forces above the surface that shaped this feature?

Another favorite of mine is what I've named the "squid alien" rock, because it looks like a cute and squishy creature from outer space. I'm fascinated by how round it is! I know that wind blows bits of sand around which polishes rocks over time, but how does this rock appear to have a "head" and three little "legs"? Not only that, but it also seems to be attached to the rock below it. This wasn't the only such rock I came across either. What did this rock initially look like for it to eventually assume this shape?

I almost didn't spot this formation while hiking, but despite its relatively small size, I felt it was one of the most fascinating things I found! I found it on a pretty large, unassuming rock. It appears as if this area had more time to crystalize compared to the rest of the rock. The way that it looks like it's pouring out is also fascinating. Whatever it is, I think it's really cool.

Overall, it was incredibly fun to visit my favorite local park with the insight I've gained from this class. It's made me think of these rocks and their structures in completely different ways than before! It also makes me appreciate them even more, as every rock has a story to tell and they're only here today because they have undergone seemingly countless different processes beyond our own scope of time.

Other things I found on my hike

I saw quite a few little cacti. They're especially beautiful this time of year.

Many lizards were spooked during this hike, but there were also quite a few brave ones that let me get close!

This lizard holds the honorary title of "chunkiest known lizard in Horsemen's Center", as so far I've never found any other lizard bigger than him.

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