Updated 9/18/2014. I just realized that I had linked to the part 1 video and then the part 1 again. Oops! The link is updated now and it should make a lot more sense!
Oh my, a three-part post about just one place?! Yes, Yosemite is a huge park with lots to see, and in our three days there, I feel like we only scratched the surface. At least we saw enough to know that there is much to do there, and we need to return.
On the morning of June 24th, we woke early, broke camp in Tuolumne Meadows and headed West and South toward Yosemite Valley. The drive was filled with ooohs and aaahs. We drove past El Capitan, then Half Dome. Yosemite Falls was flowing beautifully.
Having not been in Yosemite Valley before, I was a little surprised how many people (and cars!) were packed into the relatively narrow valley. The place bustled almost like a city. Between the valley walls were packed two roads (one Eastbound, one Westbound), some bike paths (a great way to relieve some of the road congestion), campgrounds (for those who book nearly a year in advance), lots of buses, the Merced River, Visitor Centers, in some areas a wide meadow, and lots of people. We knew Yosemite was a very popular summer destination, but driving and parking were a bit more complicated than I had planned. Still, the place seemed to run smoothly and we got to the Visitor Center almost on time. We had been given permission to park near the Visitor Center in an area designated for employees, which was nice. When we arrived we gathered our gear and headed right past the mule deer munching grass on the lawn of a chapel toward our meeting place.
Ranger Erik Westerlund was there to meet us. He said that he thought he’d walk us through his usual geology talk which he regularly presents to groups of visitors. We didn’t catch the beginning of the talk on video, so it starts off a little bit into the discussion. Ranger Erik is a biologist and always thought geology was boring, until two events changed his mind. I’ll let him tell the story. I will say it’s interesting to get two biologists together to talk about geology. He and I both kept interrupting the geologic story with “hey look, a Steller’s Jay!” and “is that milkweed?” and “how is the health of your monarch butterfly population?” I edited most of that out, but I might put together another video at the end with all the extraneous plant and animal talk. There are some really interesting stories in there! And besides, geology is Boring. Right?
And this is one of my favorite pics from the trip:
I split the videos up in two so that they weren’t so hard to upload. Here is the first video. In this video, Ranger Erik explains how subduction of the Pacific oceanic plate under the North American plate along the coast of California caused the Sierra Nevada range to be uplifted. The Merced River cut the V-shaped Yosemite Valley. Then, much later, glaciers carved the valley. Since then, it has filled in with sediment to a very great thickness!
Before Erik explains why he finds geology interesting now, although he thought it was boring before, I think I should explain a few things.
Firstly, Erik talks about endemic species and endemism. I doubt my new students will know those words yet. Endemic species are species that only live in a certain area. We discussed the fact that California has a high degree of endemism, which means that there are many species that only live in California.
Secondly, I think a refresher on evolution is probably a good idea now. Erik finds geology interesting because in California, as in many places, geology has been a direct driver of evolution. There are several things people misunderstand about evolution, so let’s clear those up. First of all, individuals do not evolve; populations evolve. Secondly,evolution is simply a change in how common each genetic trait is in a population over time.For speciation (one population splitting into two species) to happen, there are certain criteria that must be met. Here is how a new species is formed: 1) The population must have some genetic diversity within it. If all the individuals within the population were the same, the population could not evolve. 2) Some members of the population have to be separated from other members for a long period of time (this is where the geology comes in). 3) In one of the two populations’ ecosystems (or in both), there has to be some environmental difference from the original populations’ ecosystem. It could be a climatic difference, it could be a different predator, or it could be a difference in vegetation. It could also be a social or behavioral difference. 4) In this new environment, some members of the population may have genetic differences that result in them being more successful at competing for resources (we call this “better adapted”) than other members. 5) As a result of this difference, the more successful ones will either have more offspring, or have more that survive. 6) The offspring will have the more successful traits passed on to them, so the more successful genes become more common within the population in the next generation. 7) Eventually, one population becomes so different from the other that they no longer can interbreed. They are now two different species.
So now, see if nunataks make sense as drivers of the evolution of the Lyell salamander! (<– This is the link I messed up before.) I find it so interesting that California is a biodiversity hotspot, in part due to glaciers! Indiana had glaciers, too. Anyone want to guess why Indiana doesn’t have a high degree of endemism?
Upon finishing the geology talk, we asked Erik for a recommendation on a trail. He suggested a hike up to Vernal Falls. We also got on the subject of food and he suggested Ramone’s Taco Truck. That is the beginning of another story that I will tell in the next post.
On the way to Vernal Falls, we saw some interesting things, including this bear trap in the campgrounds. I wondered how often it became a curious kid trap! Shortly after passing the bear trap, this little thing walked right past us along the sidewalk:
At the trailhead, we enjoyed the view of the river:
The trail to the falls is paved, popular, and a fairly steep up, up, up. There were lots of squirrels who were looking for some easy lunches in the form of handouts from hikers. They didn’t mind being petted at all. We didn’t pet or feed them for a couple of reasons… one because it is not good for them to become dependent on summer handouts, then have difficulty finding food for the winter, also because the little guys can carry fleas and diseases. Lots of other people enjoyed playing with them, though. I just enjoyed the fact that they seemed happy to model for my camera.
Along the trail, there were a few places to stop and take some family portraits. One of my favorite things that happens along populated trails is the little interactions with other hikers. We offered to take a picture for a Japanese couple and their two little kids and they took a picture for us. This is one of the few “all four of us” pictures we got on the trip:
It wasn’t long before we were at the halfway point. We were tired and had a bit of a drive to Merced, CA that afternoon, so we decided not to go to the top. Here is the view of the falls from the bridge at the halfway point:
Once back in the valley, we hopped in the truck and headed off toward Merced, with visions of delicious taco truck burritos dancing in our heads.