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.
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.
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.
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.
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.
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