In the spring of 2006, which would have been the second half of my freshman year at Purdue, I took a Geology class (EAS 111), because I needed a lab science. I’m not sure if I was aware of it at the time or not, but it had a 3 hour lab attached to it. A lot of the instructors who ran these labs were aware of how painfully long that is, and usually let out early.
Not my guy.
I think I had the Associate Professor Deanish President-Elect Acting Chancellor in charge of EAS labs, because he never let out early. In fact, he started every lab by reteaching what had been presented in the lecture that week.
But that’s okay, because this guy was awesome at Geology. He knew everything. Probably better than the lecture professor did – and he was hands on.
Anyway, he gave us an extra credit assignment – a self-guided field trip around Purdue’s campus to find and identify geological wonders. I recently found my submission for this assignment, which I received full points for. Not because I was correct in my identifications (which I am pretty sure I was, for the most part, not), but because my paper was (in his words) “the best thing he’d ever read”. He also told me that I would most certainly get an A in his lab regardless of how correctly I identified everything as long as I kept making him giggle the way my extra credit assignment did.
So now, I present to you, my submission for EAS 111’s self-guided geology field trip.
Wouldn’t It Be Gneiss?
A Geology Field Trip
March 8, 2006
Rock one seems to be granitic in composition. It is light colored, with small amounts of pink, suggesting the presence of quartz or K feldspar. It has a medium grain size, with the majority of the grains moving in the same direction. I would just call it granite, but I have a sneaking suspicion that it’s some type of gneiss.
Rock two was all kinds of weird lookin’, I am not gonna lie. It was dark, with a fairly uniform grain size. There were lighter colored “veins” criss-crossing the entire thing. Unfortunately, I haven’t the slightest idea what it is. The first time I looked at it, I thought it might be a sedimentary rock with large pieces cemented to each other, but after a closer examination, I think it’s some sort of metamorphic rock.
Rock number three was like some kind of prehistoric beast, sitting in its ring of trees waiting to jump on some poor kid’s compact car. I noted foliation, and that it was a dark stone, with very small crystals. For some reason, I was under the impression that it was basaltic in nature. I would say it is metamorphic, and an example of a hornfel or an amphibolite.
At first, I thought that the steps were stop number four. Then I took a better look at the paper. Ahh, the pillars. They are definitely a limestone (sedimentary), and though I’m leaning towards oolitic, I could be wrong. They have a light, sandy color.
As I approached rock number five, I said to myself “That looks like a sandstone.” Of course, I had to go sit and play on it before I was absolutely sure, but it is definitely a sandstone. It has a light, tannish color, and very small particles. I would classify it as an arkose sandstone.
I have rock number six marked as “igneous, possible metamorphic”. That seems to be the theme in my observations. It has whitish gray and black particles, and a “salt and pepper” look. The crystals are fairly small. I identify it as diorite.
I noticed some distinct foliation on rock number seven, and from basic observations I determined it to be a granitic gneiss. The pinkish color is consistent with K feldspar or quartz, suggesting granite. I also enjoyed the many quotes dotting the landscape around rock number seven. If it isn’t a philosophical rock, it should be.
I stood in the Stewart Mural Room for about ten minutes until I realized the rock I was to be looking for was probably the room itself, in other words, the marble walls. It’s very good looking white marble, and is a metamorphic rock coming from limestone. I wish my mural room was made out of marble. I also very dutifully noted the dark granite steps leading up to the doors to the Stewart Center. They were very nice. I even took a picture, but I keep that under my pillow.
The rock opposite Stone Hall appears to be igneous, with some quartz present – fairly large crystal size. It is a dark stone, crossed with white and pink “ropes”. It’s also very old, and I’m assuming it hasn’t changed much since 1887. There’s a chance the dark sections are gabbro, but I’m not holding out.
Stop number 10 was a little tricky to find, but I was looking in the wrong place. I did find it though, and have it marked as a clastic sedimentary rock with a large (1–4 in.) particle size. The particles are angular, and are held together by a dark cement. From this, it appears to be a breccia, and it also looks like the sediments didn’t get very far before they cemented into place. I wonder how they feel about that.
The fountain in Founder’s Park is made of the metamorphic rock marble. It’s just as nice as the marble in the Mural Room, but it’s darker, with more pink, black, and green, although the green may be due to water damage. It reminds me of my kitchen countertops, only more round and taller.
Okay, rock number twelve was in the middle of a cluster of thornbushes. I got a chuckle. I mean, if I were designing a field trip / scavenger hunt, I would make it as hard as possible. Anyway, the definite foliation suggests a metamorphic rock, with a fairly small crystal size. The colors range from reddish orange to black. SO I would call it a staurolite-quartz-garnet schist, but that’s just me, and me’s wrong a lot. In other words, I don’t know about this one.
Rock thirteen is a metamorphic rock with definite layers that curve around. It looks like there is some quartz present, along with some K feldspar. The crystals range from small to fairly large in size. It could be a granitic gneiss. Or it could be a Quartz-K-feldspar schist. Some scholars maintain that the actual identity of this rock has been lost forever. Who am I to argue with that?
Rock fourteen was pinkish, with thick layers of large crystals on layers of smaller ones. It probably contained a lot of K Feldspar and quartz ( I seem to see them everywhere.) The layering suggests to me a metamorphic rock. I would say that this rock is a gneiss, and a guartz-feldspar one at that. It seems to be a common thing to call a rock when you don’t know what it is.
Here it is. The last rock on this roller coaster of discovery, joy, frustration, and confusion. At least I did it when it wasn’t raining. This rock is yet another metamorphic rock, ascertained by the definite (definite, mind you, I wrote it down) foliation. I saw “lots of darker minerals” and some pink and white hues. Oh, and there was some green as well. Yet again, I’m going to have to go with some sort of gneiss with this one, but I think this time I might be right about it. And wouldn’t you know it, I’m going to say granitic gneiss due to the fact that, gosh-darned it, it looks so much like a granite that had all the colors separated and smashed into separate layers by extreme pressure and heat. Or something like that.
Well, I enjoyed going on this field trip. Hopefully, you enjoyed reading about it as much as I enjoyed writing it and hitting the “text-wrap” button on the picture toolbar every few minutes. Rock on!
So there you have it. Apparently, I am an idiot. Next time, I’ll share with you the report I did on graphite!