Geology Field Trip, NYC

[nycgirl]

Recently I went on a field trip in the city for a geology course that I'm taking. I had to do a report on it, so I thought I might as well post what I came up with. While geology isn't my strong suit, or any of the sciences, I still found the trip interesting.

Our destination was Central Park, but our instructor stopped and lectured on many of the buildings on the Upper East Side on the way. This office building has a facade made of sandstone, a hard sedimentary that can nevertheless be carved, as evidenced by the intricate decorations. (I diligently took notes, but my nonscientific mind was thinking about the cute but stern-looking animals, and wondering if the creatures that look like dogs with wings had a name.)







This quartz-dominated sandstone has a lovely pinkish color and striations resulting from weathering.



Limestone, a sedimentary rock composed primarily of calcite, is also commonly used in architecture.



These blocks of fossiliferous limestone contain the fossils of ancient coral. (I was supposed to use some sort of scale in all my photos, but I did it exactly once and got too preoccupied to keep up with it.)



Limestone is not the most resistant rock. These blocks of oolitic limestone show signs of weathering due to low acid levels in rainwater.



Oolites are small, rounded grains that form in warm, shallow, oxygen-rich marine waters. A close look reveals signs of mollusks and crustaceans.







This wall, consisting of the igneous rocks granite and gabbro, is unusual because the block of granite is on the top and gabbro on the bottom. In construction, it is typical to use the highly durable granite as a foundation, but gabbro, a mafic rock, is even stronger.



A close look at the granite reveals that it contains xenoliths, rock fragments that are enveloped into magma while it is still fluid.

[onlymark]

I caught a small part of a programme once about a (archaeology, geology?) student who was fascinated by the amount of fossils that could be seen in buildings in cities and on pavements etc. I bet there's a lot more than we realise.
Anyway, I am enjoying this and look forward to more.
By the way, has the building with the flying dogs got any connection to Zoroastrianism? These sorts of carvings were associated with certain countries before the onset of Islamic designs, at least that's what I think and I've seen something like them reasonably often on ancient sites in some Arabic countries.

[nycgirl]

Now we come to Central Park, which surprisingly still has some pretty foliage, even after Hurricane Sandy.



My teacher turns our attention to the walls surrounding the park, something I never once thought about in all my years of coming here.



They are made of a type of sandstone, although geologists are unsure of what type exactly since extreme weathering has made it difficult to identify. The patterns on the rock, to my surprise, are natural and point to biological activity.





Central Park, one of the most beloved sights in New York City, is considered to be a masterpiece of urban landscaping. Its designers Frederick Law Olmstead and Calver Vaux constructed it with the goal of “preserving and enhancing” the natural terrain, and in my opinion, they greatly succeeded. It's easy to forget you're in the heart of a concrete metropolis when you're there.

Scattered throughout the park are outcrops of the Manhattan Formation, a metamorphic rock estimated to be 400 to 500 million years old. The Manhattan Formation is a mica schist, a rock so strong that it is used as the foundation of many of the city’s skyscrapers, including those of Columbus Circle, seen here.

Digressing from geology a bit, I just want to point out that the tall building in the background is the one I mentioned in my Hurricane Sandy thread. It caused quite a stir when its crane collapsed during the storm. Fortunately, it didn't fall down. It's set to be one of the tallest buildings in the city when it's completed in 2013.



Back to the lesson. Here we can see that glacial activity has carved crack-fractures into the rocks. Geologists can use these fractures to determine which pieces of rock scattered throughout the park were originally part of the same rock.





Over time, even the highly durable Manhattan Formation has become weathered, exposing resistant veins of quartz.



My teacher had something to say about the base of Balto's statue, but I have no idea what. I was distracted by the placard dedicating the memorial to "the indomitable spirit of the sled dogs that relayed antitoxin six hundred miles over rough ice, across treacherous waters, through Arctic blizzards from Nenana to the relief of stricken Nome in the Winter of 1925." Really interesting story.



And that's all I have. None of this is new to a casual geology buff, of course, but I found it really interesting, despite my lapses in attention. I'm glad I got the opportunity to look at my city from a new perspective.

[onlymark]

"The patterns on the rock, to my surprise, are natural and point to biological activity."




Errrrr.......................... how can I put this diplomatically and convey the thought nycg that I think somehow a slight mistake has been made, not by you but by the teacher? I could easily be wrong as I am no expert on geology but I am quite good with my hands - and, diplomatically I think that is utter crap.
More in a minute. Bear with me, I need to find a photo.

[onlymark]

I say they are chisel marks from a Mason.
This are the sandstone arches on my terrace -



Closer -



Made by chiselling in a regular pattern into the stone. Note the square corners to some of the marks -




Yes? No? I willing to be shown up as having no idea.

[nycgirl]

You sure are quick on the draw with your pictorials, I'm impressed. Yes, I also was a little skeptical and I (briefly) searched the Internet but could find nothing. I hate to dispute a teacher (I'm such a dork), so I'm wondering if maybe she spotted some prehistoric claw marks or something and I missed it. At any rate, your chiseled sandstone looks very alike.

The fossils are neat, aren't they? "Discovering" them was my favorite part of the field trip.

Thanks for mentioning Zoroastrianism. I find it's hard to do a search on something if all you have to go on is "flying dogs." The building housed doctors' offices, but I have no clue on what type of doctor.

[Deleted]

Paris is mostly built out of sandstone and limestone -- granite for the impressive stuff.

[tod2]

nycgirl - So glad you are doing this geology course as you will doubly appreciate the rocks in Kruger Park!
I think Mark is 100% right about the coping on that wall - being chisel marks. Almost seems like it was the same chiseler ;D

It's bedtime now, but when I get a chance I will give you some information about the Kruger landscape that you won't find in their handy "animal spotting" books. I will put it here shall I, or under Kruger Prk?

[onlymark]

nycg, you've seen the rocks in a couple of my reports on Jordan?

[Deleted]

Are there rocks in Jordan?

[onlymark]

I've seen one or two.

[mossie]

I would agree about the chisel facing finish, when I saw the pic it hit me. But limestone is fascinating stuff, the basic material ranges all the way from soft chalk through ragstone, limestone to marble. The base material ranges from algae and fossils of minute plankton etc, all formed by compression over millions of years. The odd seashell falling into this gives those fossilised impressions.
Where is FMT when we need him He should know all about stone
I just picked up a rudimentary knowledge from buying and coating and laying all types of stone over nearly 40 years of misspent adulthood. ;D ;D Anything to keep the wolf from the door.

[lola]

Oh, cool, nycg. I love geology; the easy part anyway. Fun to see fossils in the limestone, and that beautiful sandstone.

Very broadly speaking you could call a man chiseling "biological activity." I have to think the chances of natural formations that could happen to lie flat and true all the way up 5th Avenue to be mighty slim. Possibly your prof was pulling an old geologist joke on the class.

[bixaorellana]

This is just immensely cool, NYCGirl, and so beautifully photographed. Love your explanations!

I was particularly excited to see this as I was so struck by the building facades in Florida that had fossils in them. I saw them in Panama City, I believe, & in Fort Myers. I couldn't believe people were just casually strolling past without stopping to scrutinize all the fascinating evidence of ages past.

I think the teacher was correct about that coping being of naturally formed rock. To me it looks so much the way packed sand looks when waves recede, leaving behind those micro-mini dunes full of holes from tiny creatures hiding in the sand. The worked stone example Mark shows is not at all the same, at least not to my eyes.

[htmb]

Very cool report, nycgirl. I sure wish I could remember all that information, but your report will remind me to look more carefully at stone buildings.

[nycgirl]

Dec 5, 2012 17:42:27 GMT tod2 said:

nycgirl - So glad you are doing this geology course as you will doubly appreciate the rocks in Kruger Park!
I think Mark is 100% right about the coping on that wall - being chisel marks. Almost seems like it was the same chiseler ;D

It's bedtime now, but when I get a chance I will give you some information about the Kruger landscape that you won't find in their handy "animal spotting" books. I will put it here shall I, or under Kruger Prk?

I'm so excited! Only 23 more days!

Sure, post it here or there, either is fine by me. Although I won't be sorry to revisit your Kruger thread.

[nycgirl]

Dec 5, 2012 17:55:47 GMT onlyMark said:

nycg, you've seen the rocks in a couple of my reports on Jordan?

Yes, and they're beautiful. The landscape reminds me of the American Southwest.

Dec 5, 2012 17:39:59 GMT kerouac2 said:

Paris is mostly built out of sandstone and limestone -- granite for the impressive stuff.

Yes, granite is more expensive, but worth it. You can really see the difference in things like gravestones. There are centuries-old granite gravestones that are still be legible, whereas limestone gravestones that are only decades old show can be severely eroded. The cemetery stalkers on this forum are probably aware of this.

Dec 6, 2012 1:41:28 GMT lola said:

Very broadly speaking you could call a man chiseling "biological activity."

Ha ha, true!

Thanks for taking an interest in my little field trip, everyone. If I find out I was way off base when I get my report back, I'll be sure to make corrections.

[tod2]

Ncygirl - I thought about it and don't want to intrude on this yet unfinished photo-essay of yours!
So, I am posting my geology findings on the 'Kruger story' - that way if I find more info for you I can add to it.

[nycgirl]

No, not at all, I don't have anything else to post.

[tod2]

Under my Kruger story I've done the introduction to the geology of Kruger National Park, and have a bit more to add.
Off to work now. Hope you find it interesting

[onlymark]

Similar?

[nycgirl]

It does indeed look similar, Mark. But then I read Bixa's comment and her explanation sounds totally plausible, too.

So, I got my report back and I got an A. My teacher said I could have gone into more detail (as I said, my mind was flitting on other topics), but it was well-done overall. I was wrong on some things, though. Apparently my photo of the sandstone doesn't have cross bedding. Also, it turns out gabbro is mafic and therefore stronger than granite. She gave no comment on evidence of "biological activity" on the walls. Oh, well.

A strange thing I noticed about her corrections was she inserted the word "the" whenever I mentioned Central Park. I've never heard anyone call it "The Central Park." What the hell?

Anyway, thanks for your indulgence, everyone, and forgive me for spreading misinformation on the net.

[tod2]

Well done you! I am excited for you both about your Kruger & Southern African trip! I do hope you find a tiny little pebble to bring back and put on your shelf at home
I have so many rocks now that I cant display all at once.
Namibia is the best place for wandering off the tarred road and picking up semi-precious stones. Many little makeshift wooden stands selling them cheaply too!

[Deleted]

I thoroughly enjoyed this report NYC girl thank you.
I loved seeing the oh so familiar pics of "The" Central Park and it was very cool to have some of what I just took for granite ;)explained.

I tend to agree with Bixa's explanation as being more plausible.

The fossils are especially cool.

Thanks again for this and bravo on your grade!!

[nycgirl]

Dec 8, 2012 6:36:08 GMT tod2 said:

Namibia is the best place for wandering off the tarred road and picking up semi-precious stones.

Oooh, I'd love to do that!

Dec 8, 2012 12:29:22 GMT casimira said:

it was very cool to have some of what I just took for granite ;)explained.

Haha, I've known people who actually think that's how the saying goes!

[Deleted]

Oh, that's funny NYC girl!!
My lame attempt at early a.m. corn.......

I love your threads about NY. I want you to know, they are a combination bittersweet for me personally so I don't always launch right into them, but, you have represented NYC in so many wonderful aspects I can't begin to tell you how much I appreciate them.
I just learned this week that my brother and I are having to sell our family property up there (on Long Island) so, it is with a heavy heart each time you give a us a glimpse of a beloved stomping ground of mine and I so appreciate your generosity and ingenuity.

[onlymark]

Due to getting married in City Hall and not having enough time in the city I also always enjoy the reports.

[lola]

You got married in NYC City Hall, Mark? What a great idea.

NYCgirl, I give you an absolute A for this report and your others, too. You're a darling to bring it to us.

I hope you don't mind some of us who will never again have to fret about our GPAs making an issue of the wall. Since I live in Missouri, the Sho Nuff I mean Show Me State, I like those in authority to make a good case for themselves. And it's an entertaining question.

I would be interested, if your prof contends that the wavy surface of those walls is natural, how he would describe the quarry of origin. There are several miles of perfectly flat surfaces that would need to be cut, maybe nine inches thick. Is there a cliff face somewhere that they quarry these from? The sea bottom? Also, the capstones are cut from one piece of rock, sloping off on both sides at an angle. Mother Nature doesn't tend to work that way.

[htmb]

Would love to hear more about your marriage at city hall, mark.

Casimira, it sounds like selling your family property is bittersweet. I can relate.

[lola]

Casimira, I hope you get a chance to visit the dear old place soon.