OSU Geotour Supplemental II: Springy Rock! Porphyry!


Phase II of the Oregon State University geology tour supplemental lingers round one building only, but what a building!

Stop 7. Gleeson Hall 1

So here’s a rock type I get very excited about, not because it’s fantastically beautiful, but because I find it fascinating. Travertine! I loves travertine. Travertine is a type of limestone, but it forms from solution rather than critters, and it’s got all sorts of weird voids and textures, and it can form from so many things – hot springs! Cold springs! Lakes! Streams! Ponds! Seeps! Basically, if there’s water full of the stuff limestone is made of, it can precipitate out travertine. Evelyn can tell you why travertine’s important.

Travertine! Look at the spongy texture - all those lovely voids and streaks and such. Some of those hollows are full of tiny little calcite crystals. I could spend hours staring at a block of travertine, and find something new every few seconds.

Travertine! Look at the spongy texture – all those lovely voids and streaks and such. Some of those hollows are full of tiny little calcite crystals. I could spend hours staring at a block of travertine, and find something new every few seconds.

Weathered travertine! Note the contrast between the bit where the water really likes to run down (the gray-stained portion) and the less-weathered bit (the whiter portion). You can feel the difference: the gray bits are rough like sandpaper, the white bits are far smoother, just as it all was when it was fresh out of the shop. It's amazing what a little water carrying dissolved CO2 can do.

Weathered travertine! Note the contrast between the bit where the water really likes to run down (the gray-stained portion) and the less-weathered bit (the whiter portion). You can feel the difference: the gray bits are rough like sandpaper, the white bits are far smoother, just as it all was when it was fresh out of the shop. It’s amazing what a little water carrying dissolved CO2 can do.

Le design. In addition to the travertine bannister, there's travertine facing on the brick. The contrast between light and dark here isn't weathering - those narrow dark streaks are part of the stone itself, where dark and light bands alternated during deposition. Or so I assume.

Le design. In addition to the travertine bannister, there’s travertine facing on the brick. The contrast between light and dark here isn’t weathering – those narrow dark streaks are part of the stone itself, where dark and light bands alternated during deposition. Or so I assume.

Here's a shot that shows the alternating dark and light coloration a bit better. You can tell that some streaks look more like stains from rivulets of water that have flowed down the building, and others are incorporated within the stone. And yes, I admit it: I like fondling travertine and sometimes make trips to the Home Depot just to play with their travertine tiles.

Here’s a shot that shows the alternating dark and light coloration a bit better. You can tell that some streaks look more like stains from rivulets of water that have flowed down the building, and others are incorporated within the stone. And yes, I admit it: I like fondling travertine and sometimes make trips to the Home Depot just to play with their travertine tiles.

Now we’re going to tear ourselves away from the travertine here, and go round the other side of the building to

Stop 8. Gleeson Hall 2

Here’s a nice transitional shot: we’re still looking at travertine (and note how the portions that bear the brunt of the weather show it!), but our eyes are also drawn by the big pink steps…

The facade of Gleeson Hall, showing the travertine pillars and facing against the bright red-orange brick, and a glimpse of the massive pink stairs.

The facade of Gleeson Hall, showing the travertine pillars and facing against the bright red-orange brick, and a glimpse of the massive pink stairs.

Those stairs are wild, people. Pink porphyritic granite, with enormous phenocrysts. Megacrysts? Could be!

A part of the stairs and the massive slab beside them. I'm sure there's some fancy engineering term for this. I don't know it. Also, I am distracted by pink porphyritic granite.

A part of the stairs and the massive slab beside them. I’m sure there’s some fancy engineering term for this. I don’t know it. Also, I am distracted by pink porphyritic granite.

In the previous photo, you probably noticed a contrast between shiny bits and dull bits. This is because the surfaces people must walk on have been roughened after it was discovered that highly-polished rock + wet or icy weather = students falling on their bums.

In the previous photo, you probably noticed a contrast between shiny bits and dull bits. This is because the surfaces people must walk on have been roughened after it was discovered that highly-polished rock + wet or icy weather = students falling on their bums.

Some absolutely enormous crystals of orthoclase/perthite, and you can see the dark speckles of hornblende and/or biotite, and some nice knobby gray quartz, and it's just delicious. I love it even though it is pink.

Some absolutely enormous crystals of orthoclase/perthite, and you can see the dark speckles of hornblende and/or biotite, and some nice knobby gray quartz, and it’s just delicious. I love it even though it is pink.

And my favorite: an absolutely magnificent twinned crystal of orthoclase/perthite. Lockwood thinks it may be a braveno (alt. spelling baveno) twin - any one else care to weigh in?

And my favorite: an absolutely magnificent twinned crystal of orthoclase/perthite. Lockwood thinks it may be a braveno (alt. spelling baveno) twin – any one else care to weigh in?

Right. That brings us to the end of Phase II. Phase III will include some marble halls, and some extremely creative photo editing as I struggle to overcome the limitations of photographing subtle gray patterns in gray stone in gray twilight…

 

Back to Phase I or Forward to Phase III

Comments

  1. geocatherder says

    Ah, my favorite kind of granite. I’m not sure if the black mineral is hornblende or augite; hornblende is chemically more likely, but it usually forms more acicular (long, skinny) crystals.

  2. rq says

    Don’t know about naming the twinning crystals, but definitely a wonderful find!
    Also, if you love the combination on this building, check out the Latvian Statue of Liberty (usually known as the Freedom Monument):
    http://lv.wikipedia.org/wiki/Brīvības_piemineklis
    And lots of limestone fun here:
    http://www.citariga.lv/lat/rigas-apskates-vietas/pareja-riga/bralu-kapi/

    Yep, that’s travertine (Latvian national rock, actually). And red granite on the bottom. The lady is done in copper, which is why she turns green all the time.
    I read Evelyn’s post on travertine, so now I can enjoy a deeper, geological connection to this monument. :) Also to travertine everywhere.

  3. Stevarious, Public Health Problem says

    I’m sure there’s some fancy engineering term for this. I don’t know it.

    I believe the proper term is ‘really big rock’.

    No?

    Huh.

  4. brucegee1962 says

    It’s so odd when you come across the same word (or nearly the same) in wildly different contexts.

    #1 I first came across the name “Porphyria” in the poem “Porphyria’s Lover” by Robert Browning, a weird and disturbing little poem that starts off like one of those 1950s songs about the lower-class boy in love with the upper-class girl, but then takes a detour into psycho-land when he strangles her with her own hair so she won’t ever leave him. Last line: “And yet God has not said a word!”

    #2 I was doing research on what a real-life disease might be that could cause something akin to vampirism, and I came across another porphyria which involves a body unable to produce or absorb heme, with symptoms like aversion to sunlight, hair in unusual places, receding gums, etc.

    Now this. The word porphyria or porphyric is one seriously messed-up word!

  5. Andrew G. says

    “Porphyra” is apparently the Greek word for the murex snail and the purple dye (Tyrian purple) produced from it. The word “purple” derives from it via Latin. It’s therefore not all that surprising that it gets attached to anything that involves pinkish or purple-ish colours, whether relating to blood or stone :-)

    • says

      Yes, apparently the dye ranges from pinkish to scarlet to “actual” purple. I know this because my undergraduate Latin professors were SO EXCITED when the HBO series “Rome” showed bright red trim on the Roman senators’ togas instead of violet. (And whenever we encountered the word “purpureus” in a text, we were supposed to translate it as “scarlet”.)

    • brucegee1962 says

      Wow. I’ve been doing a bunch of research on the Phoenicians (the original purple people) for a different project, but I hadn’t come across that info. Thanks!

  6. says

    Dana, can you recommend an introductory geology book for poor old me who just thinks rocks are pretty? I like learning stuff from the internet, but I’m also a book person.

    • Lithified Detritus says

      Anything by Tarbuck & Lutgens is likely to be good. I have a 1997 edition of their Earth Science text that would take you a long way. I’m sure that you can find something used for a reasonable price.

    • Lithified Detritus says

      Also, while it is not an instructional text, John McPhee’s Annals of the Former World is a must-read for anyone interested in the geology of North America.