Accretionary Wedge #42: Countertop Geology of two marbles

The Accretionary Wedge is a semi-regular collection of geoblog posts that follow a common theme. Ian Saginor is hosting AW #42 at his volcanoclast blog with the theme of Countertop Geology. For my first ever Wedge, Ian has tasked everyone to:

  • Find great countertops or decorative/building stone, as long as it’s been “separated by humans from it’s source”;
  • Post some pretty pictures;
  • …And maybe hazard an interpretation or two.

Good thing Ian expanded this topic to include decorative and building stone, because it opened up the opportunity to show off two awesome pieces from around the Notre Dame campus. First up is the Kugel Fountain in one of our student centers, the Coleman-Morse buildingThe Marble, as some call it, “contains a 30-inch solid granite sphere which weighs 1,300 pounds and floats on 7 lbs. of water pressure” (via the ND website).

Notre Dame’s Kugel Fountain. The granite sphere constantly rotates – ‘clockwise’ during this 1-second exposure – due to minor differences in supporting water pressure.

Take a closer look…

Unlike most granites, you have to hold this one steady to get a decent photo! Large ovoid alkali feldspars (pink) enclose opaques (dark minerals, mostly hornblende), and in some cases plagioclase feldspar (gray) form rims on alkali feldspars. Click any photo to enlarge.

Continue reading “Accretionary Wedge #42: Countertop Geology of two marbles”


Low-T, high-P rheology of a Nalgene water bottle

Callan’s post on the rheology of an overheated water bottle reminded me of a little experiment from before I started this blog. I had not thought to share the results with y’all until now!

This post in a nutshell: undeformed and deformed Nalgene water bottles

This is, of course, all John’s idea. “John” is in the engineering side of our department, and he does a lot of work with concrete and steel to accomplish undoubtedly ingenious engineering…schemes. One piece to the puzzle lies in designing buildings and bridges that do not break or fall down at the drop of a hat. This involves much testing of tension and compression yield strengths of industrial materials; tests which utilize the awesomely named universal testing machine (UTM) and other implements of destruction. Our UTM can apply a force up to 600,000 pounds (300 tons; about the weight of a Boeing 747). Continue reading “Low-T, high-P rheology of a Nalgene water bottle”