This blog provides commentary on interesting geological events occurring around the world in the context of my own work. This work is, broadly, geological fluid dynamics. The events that I highlight here are those that resonate with my professional life and ideas, and my goal is to interpret them in the context of ideas I've developed in my research. The blog does not represent any particular research agenda. It is written on a personal basis and does not seek to represent the University of Illinois, where I am a professor of geology and physics. Enjoy Geology in Motion! I would be glad to be alerted to geologic events of interest to post here! I hope that this blog can provide current event materials that will make geology come alive.

Banner image is by Ludie Cochrane..

Susan Kieffer can be contacted at s1kieffer at gmail.com

Friday, January 31, 2020

The most interesting thing about the U.S. Senate impeachment hearings? THE ROCK!!

In the U.S. Senate hearings on the impeachment of President Donald Trump, the Chief Justice of the Supreme Court, John Roberts, sat high behind a dark rostrum of veined marble. It appears to be Rosso Levanto, a veined marble from Italy and/or Turkey (the name means "red from the Levant"). It is typically deep purple or cherry red (but appears black in the images I've seen on TV and on the WWW). In 1949-1950, the Senate Chamber was renovated and pilasters of Rosso Levanto replaced cast-iron originals, and the wooden rostrum was replaced with the same marble.

     One of the frustrating things to a geologist is the terminology in the building stone trade industry.  For example, here's one quote: "Rosso Levanto is a red limestone from Italy.  In natural stone trade, Rosso Levanto is often simply called a Granite" (italics by me). AAAAAUUUUGGGHHHH.....
     Although most production from quarries now is in Turkey, I found only one paper (*) relevant to this stone, and it is about the building stones from the Liguria area in Italy.  The geology of the Liguria area is complex because of a long and complicated tectonic evolution during the Alpine orogenesis. Many rock types crop out here. Some are used only locally, but others, including the Rosso Levanto marble, are shipped globally. According to (reference *,
p. 82) Rosso Levanto marble is easy to work with and results in beautiful polished slabs. The slabs are primarily used for indoor structures because they are subject to decay outdoors, but they do appear as external facings of shops, palaces and villas. The image to the right of the portal of St. Lorenzo Cathedral in Genova shows the Rosso Levanto columns at (a), the largest cylindrical columns in the top half of the image.
     According to reference *, the Rosso Levanto is an ophicalcite--a serpentinite breccia with gaping fractures filled with abundant calcite veins.  The fractures range in scale from millimeters to decimeters, and are filled with calcite, fragments of rock and calcareous mud. The ophicalcites have been used since 1200 as ornamental materials, initially as columns in churches in old Genova, and then for flooring. The stone was used in palaces and churches during the Middle Ages and Renaissance, most prominently in the San Lorenzo Cathedral in Genova (figure to the right).


*Cimmino, F., Faccini, F., and Robbiano, A. Stones and coloured marbles of Liguria in historical monuments, Periodico di Mineralogia, 73, pp. 71-84, 2003.