Mark Wilson June 6th, 2013
SCIACCA, SICILY, ITALY–Our last stop of the day on this International Bryozoology Association pre-conference field trip was to a massive outcrop of foraminiferan-rich marls known as the Trubi. A view of the cliffs with the sun setting behind them is above.
My colleague (and roommate on this trip) Hans Arne Nakrem is serving as a scale to show the regular cyclicity of these marls. Appropriately, he is from snowy northern Norway. These sediments were deposited immediately after the Messinian Salinity Crisis when the entire Mediterranean was reduced to a shallow series of evaporitive ponds. These marls mark the opening of the Strait of Gibraltar which flooded the Mediterranean Basin with normal seawater (the Zanclean Flood) 5.33 million years ago.
I wish I had better lighting to show just how brightly white these rocks are. They are now used as the base type section of the Zanclean Stage.
Here is a late addition to this post (June 23, 2013). I collected some sand from the beach in front of these chalky rocks. A close-up image is shown above. Note that the chalk itself is eroded so quickly that it leaves no trace in the sand. We see here mostly rounded quartz grains and shell fragments.
sjudge June 6th, 2013
Guest Blogger: Tricia Hall
SIXMILE CANYON, UTAH — After a couple of days seeing a good number of mountain lion footprints, Shelley and I have decided that it is best to turn the attention of my I.S. toward using our new Trimble GPS to track mountain lion movements. We have heard from the local residents that the lions are low in the mountains, and have even ran across a potential “lion den”. Along the way, just in case this project does not pan out, I have measured a few deformation band orientations so that I don’t fail I.S. Just kidding! Here’s what we’ve really been up to the past couple of days….
Yesterday, we tackled the faulting and joint sets within the Flagstaff Limestone to the west of the Sixmile Canyon Formation exposure. The Flagstaff unconformably overlies the Sixmile, and the faulting and jointing relationships will be key in interpreting the deformation bands within the Sixmile Canyon Formation. We made good use of the Trimble to map the Formation and the fault (to the best of our ability). The resulting map, even without postprocessing, shows normal faulting within the Flagstaff complete with drag folds.
Above is the jointed Flagstaff Limestone looking to the north. We measured several units of this formation to determine the offset of the faults. In addition to the Trimble, we used the brand new Laser range finder! It was either the range finder or eye heighting up the mountain…I was all for the former.
After a long day yesterday, we made it out to Sixmile Canyon this morning with the intention of measuring the major joint sets in the morning followed by deformation band measurements in the afternoon. The joint sets were harder to find than we thought, but hopefully after we go through today’s data after I’m done blogging we’ll find that we’re okay on joint sets. The afternoon was pretty warm, but there was work to be done. It was finally deformation band time! We began measuring orientations, collecting samples, and yes, we broke out the Schmidt Hammer. Schmidty proved most effective and will be put back to work tomorrow. We’re well on our way to our self-imposed 300 Schmidty hits!
Schmidty was phenomenal on the deformation band shown above.
We’ll check in later, back to Sixmile Canyon tomorrow!
Mark Wilson June 6th, 2013
SCIACCA, SICILY, ITALY–Most major conference geological field trips have a portion devoted to the culture and history of the region being explored. You can imagine the delights of this nature possible on a Mediterranean island. Today we started with the main square in the city of Noto in southern Sicily. This city had been destroyed by a 1693 earthquake and was completely rebuilt. The Noto Cathedral (above) was finished in 1776. It is such a classic of Baroque architecture that it was declared a World Heritage site by UNESCO. It is striking, especially since it is hemmed in by other buildings and so provides a sudden surprise when turning a corner. Hard to believe parts of it collapsed from disrepair in 1996.
A Noto street leading to a church. The many balconies are characteristic of the city. Since the city center was rebuilt in one go, it has a consistent architectural theme.
Our second visit of the day was to an archaeological site revealing the astonishing remains of a 4th Century Roman building called Villa Romana del Casale on Mounte Mangone near the Gela River. This huge complex is most famous for its exquisite mosaic floors, the details of one shown above (“The Little Hunt”). This features a theme throughout the structures: hunting. This is another UNESCO World Heritage site. Such culture vultures we geologists are.
Certainly the most photographed of the mosaics is this scene popularly known as “Girls With Bikinis”. It is more properly described as “women participating in the female pentathalon” because of the distinctive athletic activities shown.
My favorite mosaic is probably the most violent: a series of giants killed by Hercules with poisoned arrows. Note that the dying giants have snakes for feet. It is astonishing what these craftsmen could do with millions of tiny colored stones — and that their art has survived so vividly.
Mark Wilson June 6th, 2013
SCIACCA, SICILY, ITALY–Far too late today for more than a short post. For the first time I met in real life an animal I speak about in my Invertebrate Paleontology course: the colonial hydrozoan Velella velella. We found thousands of them on Marjate Beach on the south coast of Sicily (see below). These organisms are commonly known as By-The-Wind Sailors, and they are found throughout the world’s oceans. They are characterized by a thin vertical sail over a shelf of downward-directed polyps. The sail scoots them along very effectively across the sea surface, but once they reach a lee coast they are helplessly stranded on the beach. They are striking in their tragedy as the thin purple tissues wilt in the sunlight as if they were flowers.
More posts from this very interesting day after I get some sleep!