Geology 210, week one

This week I had my first "class." We went to Little Cottonwood Canyon to make a geologic map of the area.

As I think back on this experience, I think of how fun it was and what a good experience it was.

But I'm not sure why I think that, because I don't think I was thinking that while I was actually there. While I was there, I was thinking more along the lines of:
This crammed tent is sure uncomfortable. That outhouse smells terrible. When is it going to stop raining? My back is so sweaty. Where is that blasted contact between the Mississippian limestone and the Cambrian limestone? This mountain is hard to get up. This mountain is even harder to get down. Why does that pesky limestone look and act like quartzite? I just want to take a shower. 

But it was a fantastic experience, and I'm glad I did it. 

(I'm including pictures, but I have to make some disclaimers. First, I never claimed to be a photographer; these are meant to be informative more than they are meant to be beautiful. Most of them are quite awful. I just use a little point-and-shoot camera. This is a new camera, since my last one was six years old. I tried to take these pictures quickly, so I didn't mess with settings. Most of them have too much light.)

(Also, I was going to go into more detail about the geology, but I would have to look a lot of things up, and it would take too long.)

On Monday morning, we met up by the Eyring Science Center to load up into the geology vans to head to Little Cottonwood Canyon. I rode with a TA named Rachel, who was in my geomorphology class last year.

We stopped at a hill looking up into the canyon. Our professor, Dr. Ron Harris, instructed us. There we learned a little about the 10,000-year-old glacial moraine of the canyon and learned about earthquakes. The Wasatch Fault has an earthquake on average of every 1,250 years. It has been 1,350 years since the last one. If the "big one" hit Utah tomorrow, according to Dr. Harris, no geologist in the state would be surprised. Others might be, but not geologists.

Next we stopped at a place called Lisa Falls.

This is a place where a little stream falls down the granite. There was a lot of granite rubble; apparently there was a big rock fall there only a month ago. The granite in this area is from the Little Cottonwood stock. During the Laramide orogeny around 30 million years ago, the oceanic plate was subducting beneath the continent. As it did so, it melted rocks and a magma intrusion formed in the crust. About 20 million years ago, the subducting plate fell off into the mantle, and the area underneath the continent was replaced with hot mantle. The hot mantle weakened the crust and caused it to collapse, and it is still collapsing today. As the valleys collapse, the mountains rise from isostatic rebound, exposing the granite.

Next we stopped at Snowbird to look at the mountains. There are some interesting features here.

On the left here is the Precambrian Big Cottonwood formation on top of a granite intrusion. The brown stuff on top of the Big Cottonwood formation is the Precambrian Mineral Fork tillite. (The Mineral Fork tillite formed from glaciers.) The Cambrian Period started 542 million years ago, and everything before then is often lumped into the designation of "Precambrian," since not a lot is known about the time before the Cambrian. There was very little life in the Precambrian. (That's a structural ambiguity there: there wasn't much life, and the life that existed was very small!)

Then you can see where gray layers run next to the Mineral Fork tillite. There is an extensional fault there. Those gray layers are limestone and marble (the white bands are marble, which is metamorphosed limestone). And then on the very top is more Mineral Fork tillite and Tintic quartzite (quartzite is metamorphosed sandstone). The Mineral Fork tillite and Tintic quartzite are actually older than the limestone, but a thrust fault thrust them on the top of the mountain.

After we saw this, we headed to our campgrounds. Apparently this was the biggest Geology 210 group ever, so we split up into different camps. I had signed up to be in someone's tent, so I had to go where he chose. He chose to go to Albion Basin, which is about 10,000 feet in elevation, in the midst of a glacial cirque. This campground is more primitive, meaning it just had vault toilets, which aren't great, but I grew up with them. It was quite rainy, so we didn't do much the rest of that evening. Some of the time we sat in the vans to wait for the rain to stop. I was listening to my little MP3 player, and by chance both versions I have of Vince Guaraldi's "Rain, Rain, Go Away" came on.

In a lot of my classes at BYU, there has been one person who is really annoying in classes. This person often sits at the front of the room and always has something to say. Sometimes the comments are dumb. Sometimes the comments are obviously intended to show how much the person knows. And it is always a guy. When I took Geology 112 last winter, this annoying guy was incarnated as a middle-age man who seemed to think he knew more than he did. (For example, he once was talking about "Milo Farnsworth," when he meant Philo, and once he said that dimetrodon was his favorite dinosaur--and the professor had to tell him that it wasn't a dinosaur.) Well, this Mr. Know It All was in my camp, and he also signed up for the same tent I did. But he didn't tell the owner of the tent that he had brought a cot. Not a pad or a tiny air mattress, but a full cot. If you're going to bring a cot, you should either have your own tent, or at least inform the person whose tent you're in that you're going to have a cot. This guy continued to be a Mr. Know It All in this class, but fortunately I didn't spend too much time around him.

The next morning (Tuesday) we went out to an outcrop of the Ophir shale. Although it is called the Ophir shale, it is really slate, which is metamorphosed shale. We saw some trilobite tracks in the shale. Here we learned how to take the strike and dip with our compasses. The dip is how much a bedding plane is tilted. You put the strike and dip on a map.

Then we got our maps. They gave us maps that had some landmarks and topographic lines. Our assignment for the next few days was to go out and color in the rock types and other features on our map. We got mapping partners, and then we set out to work. Even though we had partners, we ended up staying with a whole group most of the time. My partner's name was Scott; the others in the group were named Rob, Corbin, Hannah, and Shani. Rachel the TA was with us and helped us most of the time.

Our first outcrop was the Alta stock, another granite inclusion. It had a slightly different composition than the Little Cottonwood stock. Then we found the Tintic Quartzite. The Tintic Quartzite formed in the Cambrian period, after the supercontinent Rodinia broke up. Utah at that time was on the coast, so it was a sandy beach. It is those sands that formed the Tintic quartzite.

Cut through the quartzite--and lots of other rocks--were dikes, which are igneous intrusions that go straight up. The dikes were more mafic than the granite, which means they had more iron and were darker.  Then we found the Ophir shale. The Ophir shale is also Cambrian in age; it formed when the sea got deeper and the water transgressed further onto the continent.This particular outcrop of shale was more metamorphosed than the one we had seen earlier in the day because it was right next to the granite intrusion. The heat from the magma body metamorphosed it more at that location.

My partner and I climbed up the mountain to an outcrop of Cambrian limestone. Limestone forms from calcite deposits from organisms in deep marine environments. We knew it was limestone because, for one thing, it fizzed when we put hydrochloric acid on it. This is our view from that outcrop:

And here is the limestone. At first we thought the gray band was another igneous intrusion, but it was actually dolomite, which is essentially limestone that has magnesium in it:

The weather was perfect that day. It was cool and overcast all day. We had one or two tiny rainstorms, but they were no problem. I would take a few small rainstorms in exchange for coolness.

On Wednesday morning, we headed out to the other side of the area we needed to map. The weather wasn't as great on this day. There were some patchy clouds, but overall it was sunny. We saw lots and lots of Tintic quartzite on the path up to Cecret Lake. I think they spell it "Cecret" because it's not much of a secret. There were lots of people on that trail, and we heard some kids talking about a quartzite outcrop: "This isn't clay. This is rock!" "Yeah, stone!" We could have told them exactly what it was, but we didn't. We found some more dikes in the quartzite. Then we made it up to Cecret Lake.

We ate lunch there and examined the outcrop of the Mineral Fork tillite, which we initially thought was the Ophir shale, since it was slaty. A fault has thrust the tillite on top of the quartzite. Here is a picture of the tillite on the bottom and the quartzite on the top (which is how it's supposed to be--no fault in this picture.) I didn't realize that Corbin's head is in this picture.

As we left, we saw some salamanders in the lake:

We walked through some more quartzite, and then we were at the less steep Ophir shale portion of the mountain.

Right next to this (above) particular outcrop of shale was an outcrop of limestone. I think it was just a place where the sea got temporarily deeper; I think it's still part of the Ophir shale formation. The limestone had a rough texture, so I was able to recognize it as such, since I had seen limestone in Death Valley with a rip-your-pants texture. This is my view from that location:

Then we proceeded to limestone. (This is the typical order of a transgression, or rise in the sea level--sandstone forms on the bottom, then shale on top, then limestone on top of that.) We knew that there were two formations of limestone, the Cambrian Maxfield limestone and the Mississippian limestone. (There is a disconformity there, meaning there is time missing from the rock record; there is no representative rock from the Devonian, Silurian, or Ordovician periods.) Most of the time, we thought we were in the Cambrian, but we were wrong; most of the time we were actually in Mississippian limestone. We found some shell and horn coral fossils in our various limestone stops. Sadly, I only got one blurry picture of a fossil, a horn coral. It's embarrassingly blurry so I'm not posting it. With all our various limestone adventures, we got back to camp pretty late.

On Thursday, we climbed to where we left off the day before. It was a long, steep trail, and it was muggy, so we got pretty sweaty. I couldn't go as fast as the rest of my group, but there was one girl who was really slow, so I wasn't the last one. When we got to the top, it was cold and windy and made our sweat really cold.

The limestone in that location really was Cambrian limestone (thrust on top of Mississippian from a fault). It was white marble. In the midst of one outcrop, I found the world's tiniest Christmas tree:

We got to look over Lake Catherine:

Then we made our way across the side of a mountain covered with blocks of broken granite. We found a goat skull,

a granite wall,

and a big, annoying granite pile we had to climb over.

We ate lunch on an overlook of a valley.

Then we proceeded onward. We were in a place that was quite steep, and not being very coordinated and being a scaredy cat, I went very slowly down the mountain, sometimes just squatting down and sliding on my feet. It wasn't the best way to get down, but I did find a pretty green garnet crystal that formed from metamorphism of limestone. As we came down the mountain, we had to pass through lots of plants, including burrs that stuck to our clothing. They weren't sharp; just a little poky. The burrs loved Rob's shorts, so we had some group unity by helping him remove the burrs from his clothes:

(I didn't even wear shorts. I didn't want to get sunburned, so I was completely covered up. Only my hands and maybe some of my face were exposed to sunlight.) We found lots more Ophir shale:

We could tell that a rainstorm was coming, so we couldn't spend too much time at the locations; I wanted to take a strike and dip measurement but we had to get going. And then eventually a storm hit. It was raining pretty hard, so we found shelter under some trees. They worked well at first, but then they became drippy. It was still better than being out in the open, though. It even started hailing. Eventually I pointed out that it was wetter in the trees than out in the open, since the rain had stopped. We found more limestone as we walked along. We were very annoyed with that limestone (which we had seen all day), because it looked like quartzite, and it even didn't fizz as well as most limestone does. Then we found Rachel, the TA, who was looking for us. She had spent the day at the other mapping area, so we had flown solo that day. We were all wet, so we went back to camp. We learned that everyone else at camp had gone into town and got food. Dr. Harris showed up, and we talked to him and ended up going to dinner with him.

We went to a restaurant/lodge at Alta. It was just a little place run by a BYU alum. We looked at the menus and kind of panicked. There wasn't much on the menu (our host told us that their one chef was a gourmet Boston chef), and what was there was really expensive. The salads ranged from $8 to $11. Most of the meals were more than $20. The waiter told us that the meals were pretty big; when he described the steak, he said it was huge. The TA and the five other people of my group ordered regular meals but split them, while Dr. Harris and I just ordered salads. When we got our food, we wondered why they said the portions were big, because they weren't. Few of us were actually full afterwards (we wanted to go someplace else afterwards, but it was too late). The salad was small, definitely not big enough for a meal, and most definitely overpriced. The steaks were not as big as the waiter said. They might have been a sufficient meal for one person, but not for two people, and poor college students are not going to fork over $25 for one meal. 

Notwithstanding small portions and ridiculous prices, we had a good visit with Dr. Harris. He asked everyone why they got into geology, and Rachel said, "Excluding you two," pointing to Rob and me, since we weren't geology majors. Rob was a physical science education major, and this class is required for that. Dr. Harris asked if I was also that major. I said, "No. English linguistics." There was a little bit of laughter, and Dr. Harris said (not in a mean way), "You're the kind of person I try to get out of my class," since sometimes there's not room for everyone in geology. (But I do think there were still some open spots in the class, and I did get permission from Dr. Morris, who will be teaching the class this coming week.) He did say he had no problem with linguistics, and Rachel assured him that I was a geology minor. He told us the story of how he met with the First Presidency and got them to tear down Deseret Towers at BYU, since they weren't earthquake-safe. I asked him about the crystal I had found; he found out it was garnet by scratching it into a dinner knife. (I guess that was our way of sticking it to the man--if you're going to charge so much for a meal, you should let us scratch your silverware!) We left and went back to camp, sad that it was too late to go get more food.

The last day, Friday, Dr. Harris showed us lots of things that we had missed. For example, he showed us this fault. Quartzite is on the left and shale (or slate) is on the right. The shale should be on top of the quartzite.

He also showed us this sill. A sill is a magmatic intrusion that goes in between the bedding planes of sedimentary rocks, in this case shale. We had puzzled over this earlier, because we thought it was shale intermixed with quartzite or limestone. But when Dr. Harris showed us, it was so obvious that it was granite that I don't know how we thought it was sedimentary. But it did explain why the shale was so warped.

He also showed us a place where there were garnets that had formed in the aureole (a place of intense metamorphism). I don't think any of the garnets were as big as the one I found.

It was cold and rainy--more like November than August--so we left. We went to a posh resort to finish working on our maps. And we were so excited to come back to Provo and take showers.

I came home with a bunch of rock samples. It seemed like a good idea at the time, but now I think, "What am I going to do with all these rocks?" Except for the garnet. The garnet's pretty cool.

I did take a razor with me, but I didn't shave. I don't think the geology department cares whether I shave, so I'm growing my beard out until school really starts. I've never done so before. This is my beard as of Friday night (it's darker than it looks in this picture):

Then on Saturday we had to go to class to refinish our maps based on feedback the TAs got us. I got Bs on most of my stuff, so in this class I probably won't get the kinds of grades I'm used to, but oh well.

This class did make me a little sad. I'm getting close to the end of my geological career, and this class made me realize I'm not cut out to be a geologist. I just didn't see the same things everyone else saw. Also, geologists are better hikers than I am. I was slower than most of my teammates, and Dr. Harris walked really fast. I suppose that's why I'm going to be an editor instead of a geologist.

And no, I didn't lick any rocks on this trip.