mpollock January 31st, 2012
Wooster, OH – Volcanoclast is hosting the latest Accretionary Wedge, and since I have exactly 2 hours left until the end of January, I thought I’d post a last-minute entry. The theme is countertop geology, or more broadly, stones that are “decorative and completely detached from their origin.” My contribution is inspired by my weekly “Research Friday” routine.
Perhaps the most crucial countertop in my life is the one at the Old Main Cafe, where my Research Friday mornings begin. Photo courtesy of Matthew Gardzina.
While waiting on my caffeinated beverage, I admire their choice of countertop: a perthitic, alkali-feldspar-rich "red" granite.
Leaving Old Main, I pass the Kauke Arch (shown here packed with snow) and the Old Main patio (on the garden level below the arch), which are paved with anorthosite tiles. Photo courtesy of Matthew Gardzina.
If you look closely, you can see the striations and play of colors in the plagioclase crystals.
With my latte in hand, I make my way to the Timken Science Library.
Not only do I get to see this gorgeous granite at the Timken check-out desk, but also on the entrance floors and caps of the entryway walls.
I wonder…would my Research Friday routine be different if I weren’t an igneous petrologist?
Mark Wilson July 11th, 2011
STOCKHOLM, SWEDEN–I had not realized how much water is in the city of Stockholm. Almost a third of the city’s area is water because the center is built on 14 islands connected by bridges and ferries. “The Venice of the North” some call it.
Rachel, Nick and I are here for a very short visit. We’ll spend tomorrow in the Naturhistoriska Riksmuseet (Royal Museum of Natural History), so for now we just explored the neighborhood around our hotel. It is called Östermalm and is one of the older parts of Stockholm.
The Nordiska museet (Nordic Museum) has a glorious array of building stones, all from Sweden. The simple blocks are sandstones and fine-grained metamorphic rocks, and the carved pieces are limestones.
The local bedrock is 1750-1900 million years old, formed during the Svecofennian (Svecokarelian) orogeny. The outcrops I saw, like this example of “living stone” at the base of a building, are metavolcanics (metamorphosed volcanic rocks, usually basalt). Apparently the bedrock of Stockholm is an engineering geologist’s dream because of its stability, moisture repelling capabilities, and uniform strength — great for bridge abutments and subway tunnels.
I spent my Stockholm afternoon in the museums found in an easy walk around our hotel. I was impressed with the Viking runestones on display in the Historiska muséet (History Museum), and I was touched by this one. The runes are translated as: “Una/Unna had this stone raised in memory of her son Eysteinn who died in christening robes. May God help his soul.” They are carved in a glacial granite boulder, the kind of rock we saw scattered across the Estonian western islands. Note the dark xenoliths.
Mark Wilson June 29th, 2011
Like a lonely little onion in a petunia patch, a boulder of red granite sits on the cobblestone beach off Soeginina Cliff, western Saaremaa, Estonia.
KURESSAARE, ESTONIA–Hard-rock geologists sometimes complain that I flood this blog with too many sedimentary rocks and fossils (and just wait until I get to the Estonian wildflowers!). There are actually quite a few igneous and metamorphic rocks on Estonia — just like there are in Ohio — in the Pleistocene glacial till. They show up well on the beaches here in contrast to the sedimentary rocks around them.
A closer view of the above rock, just to show it really is granite.
Granite in action! A granitic vein through some unfortunate rock.
Mark Wilson March 17th, 2011
A granite exposure near Teutonia Peak on Cima Dome. Note our jackets and hands in pockets!
ZZYZX, CALIFORNIA–Our last stop of the rapidly-cooling day was on the huge Cima Dome east of Zzyzx in the Mojave National Preserve. The dome is so large (about 70 square miles) that it is impossible to detect when you are actually on it, but easily visible from miles away. It apparently is the eroded root of a granitic intrusion formed during subduction in the Jurassic to Cretaceous. The alkali granite exposed here is very similar to that of the Granite Mountains we saw yesterday.
Potassium feldspar crystals in the coarse alkali granite of Cima Dome.
The soil of Cima Dome is derived almost entirely from the underlying alkali granite.
Mark Wilson March 16th, 2011
Greg Wiles on the rim of Amboy Crater.
ZZYZX, CALIFORNIA–This afternoon the Wooster geologists studied two very different magma products in the southern part of our field area. After lunch we drove to Amboy on historic Route 66 and then hiked up to the rim of Amboy Crater. Here we saw the extrusive, mafic rock basalt at its finest in the cinder cone itself and the lava flows across the valley.
Desert iguana on the basalt near Amboy Crater.
After Amboy, we traveled north to the Granite Mountains and examined wonderful alkali granites weathering into rounded boulders. The feldspar crystals in these intrusive felsic rocks were extraordinarily large and numerous, and there were many xenoliths scattered throughout. The countryside here was lush with desert vegetation that made our all-too-brief stop most enjoyable.
An exposure in the Granite Mountains, California.
The feldspar-rich alkali granite in closer view.
Mark Wilson June 20th, 2009
There is an exquisite archipelago of thousands of islands between Finland and Sweden. I took a six-hour ferry ride this morning from Turku in southwestern Finland to Mariehamn, capital of the Åland Islands, where I am spending a day and an evening. Most of the islands are formed of a brilliant red Precambrian granite, polished smooth on the top by glaciation. Scraggly pine trees grow in the cracks they can find in the bedrock, reminding me of the terrain in the High Sierra just below tree line.
N 60.08276°, E 19.93422°
A close look at the granite shows a wonderful mix of potassium feldspars, clear quartz, and flecks of biotite. The weathered surfaces are thickly covered with colorful lichens, which are symbiotic associations of algae and fungi.
These islands have an unusual political history. They are populated almost entirely by Swedish-speakers, yet are a province of Finland. Various international agreements in the 19th and 20th Century gave the islanders autonomous status within Finland and, most famously, completely demilitarized the islands, a status they managed to retain through two world wars and the Cold War. They have their own government with a premier and parliament, they fly their own flag, and they print their own stamps.
And there you see the attraction Åland has for a geologist. Any place that features geology on its stamps deserves a visit!
Mark Wilson June 18th, 2009
I’m between geological field trips right now. I left Russia by train through Karelia to Helsinki, Finland. It was a remarkable trip through woods and villages, with the swampy environs of St. Petersburg giving way to higher and drier ground where ribs of granite occasionally showed. Next week I go to Spitsbergen in the Arctic to look at a Jurassic sequence for a few days, and then I meet two Wooster students, Palmer Shonk and Rob McConnell, and an Ohio State University paleontologist, Bill Ausich, in Estonia where we will work in the Silurian with our Estonian colleague Olev Vinn.
Helsinki is, of course, a highly cultured city with many attractions. I don’t want to minimize those, but since this is a geology blog, we must note the gorgeous granite mounds which dot the city.
They were polished smooth on their upper surfaces by Pleistocene (and Holocene) glaciers, which left classic striations showing the direction of ice movement. The Finnish Parliament building is in the background.
Tomorrow I leave by train for the ancient city of Turku on the southwestern coast of Finland, and then the Aland Islands for a quick look. It’s a tough job, but someone has to do it.