Mark Wilson June 8th, 2013
MILAZZO, SICILY, ITALY–The pre-conference field trip of the International Bryozoology Association has now almost completely circled Sicily. We are in the far northeastern corner of the island on a rocky cape jutting into the sea towards mainland Italy. The drive here along the very steep and rocky north coast of Sicily was fantastic, especially the seaward views of the volcanic Aeolian Islands (including the famous Stromboli).
Our day started on the furthest western part of Sicily. We took a short boat trip into the Stagnone di Marsala lagoon to the ruins of the ancient Phoenician walled city Mozia. The top photo is a view of the silted-up south harbor of the island with remnants of its guard towers on either side of the narrow entrance. Mozia was settled in the 8th Century BCE as a commerce center. It was well-suited to the Phoenician way of life with its small but safe ports and a defensible interior. The island is in the middle of an extensive lagoon which protects it from the ravages of the open sea (and invaders — for awhile). The site is still being actively excavated and studied.
There is a small museum on the island full of artifacts. It appears that the lagoon itself has abundant deposits of detritus from this active community, so items are continually dredged up.
Mozia has a considerable necropolis, as you would imagine. Many of the best sarcophagi and other memorial stones are in the museum.
There is a collection of terra cotta masks in the museum of apparently ceremonial use. This one seems delightful until you learn tat one of those ceremonies was human sacrifice, primarily of children. Now this character looks far more sinister.
Greeks under the tyrant Dionysius captured the island and is city after a siege in 397 BCE. The fall of Mozia is recorded subtly by remnants of literally last ditch earthworks and fires. The stones of this guardhouse along the wall on the southern coast were reddened when the associated wooden structures were burned either during or just after the siege.
The island museum has a diorama depicting the final breaching of Mozia’s walls by the Greeks in 397 BCE.
The Stagnone di Marsala lagoon was formed during the Pleistocene as an abraded marine platform cut into fossiliferous marls and soft limestones. In this view from the island to the mainland you can see six whitish piles of salt on the distant shore. These are harvested from low ponds with walled enclosures (see below). The windmills, iconic for this area, pump water from one pond to another to control the mineral phases of the precipitates. This salt production goes back to antiquity.
Mark Wilson June 7th, 2013
MARSALA, SICILY, ITALY–This morning the pre-conference field trip of the International Bryozoology Association headed into the mountains of central Sicily. The roads were steep and windy, as one would imagine, and the views of mountainsides, villages and fields spectacular. We were high enough to be in some small woods and scrub forests. Our goal was to see some mysterious blocks of Permian limestone seemingly out of place on an island dominated by Cenozoic sediments.
We met a team of friendly geologists from the University of Palermo in the Sosio Valley near Palazzo Adriano. They were well prepared to tell a complicated story of tectonics in the classic geological manner: maps and charts held by students as a professor lectures. It was very effective, aided by the superb weather and amazing views.
In this geological cross-section, the Permian rocks are shown as blue. Already you see something odd with the same color of rock above and below the blue, showing that it is tectonically bounded. It is part of a melange (in the geological sense) of blocks of rock broken and thrust about during the tectonism of the Miocene. The Permian rock was recognized as such by its fossil content, which includes distinctive conodonts, fusulinids, brachiopods, bryozoans and corals. It sits surrounded by much younger Miocene sediments, demonstrating the complex tectonics leading to this unusual setting.
Above is the Permian outcrop in the Sosio Valley. It stands out as very different from its surroundings by its lithology alone. I admire the geologists, though, who found diagnostic fossils within it — I saw just a very few highly recrystallized fusulinids and corals.
For lunch we went to the city museum in Palazzo Adriano and had delicious sandwiches and cakes. There we saw some of the best fossils from the Permian outcrops on display.
This is one of the churches in Palazzo Adriano on the city square. It looks to be neglected on the exterior, but inside …
… it is elaborate and well-maintained.
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.
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!
Mark Wilson June 5th, 2013
NOTO, SICILY, ITALY–Our last stop of the day on this International Bryozoology Association field trip was on the southeastern coast of Sicily just north of Syracuse at Scala Greca. There are several very small bays here which have been used for fishing boats since very ancient times. The whote rock is the Calcari di Siracusa (Miocene).
The rock is made predominantly made of little algal and bryozoan spheres called rhodoliths. They rolled around on a shallow, warm seafloor and are quite common in some parts of the tropics today (although with fewer bryozoans).
This part of Sicily was an invasion area by the Allies in World War II. This grim German pillbox overlooking the coast is a reminder of those times. More on this later.
Finally, I wish to record part of my dinner this evening! I ate every piece of octopus in my large shell bowl. I saw it as a duty.
Mark Wilson June 5th, 2013
NOTO, SICILY, ITALY–Our second stop of the day on this International Bryozoology Association field trip was in an unimpressive ditch (above) near Megara. But, of course, there is paleontological gold here: an assemblage of extremely well-preserved marine fossils.
Colleague Andrej Ernst is examining a layer of shells extending the length of the drainage ditch.
Her are some beautiful pectinid bivalves (scallops) with the treat for me: abundant serpulid worm tubes. There is an extensive sclerobiont (hard substrate dwelling) community on these shells.
Turritellid gastropods (snails) are extremely common in this assemblage. Note that several of these specimens have small holes drilled in them by predatory gastropods. We found naticid gastropods here too, which were probably the culprits.
This mother lode of fossils was guarded by a herd of horned beasts. This one had a bell on it, so I assumed it was the most dangerous and stayed far away. (Love this new zoom lens!)
Mark Wilson June 5th, 2013
NOTO, SICILY, ITALY–The first stop on our International Bryozoology Association field trip today was a newly-opened quarry near Cugni di Rio in the dry southeastern countryside of Sicily, a view of which is above. New quarries are always interesting to geologists — a new view of the Earth’s bones.
This is a portion of the quarry wall with the inevitable volcaniclastic unit of ash and marine sediments shown as the greenish layered unit above and below limestones dated as Tortonian (Upper Miocene). On top of the ash you can see what look like tubes sticking out of the brownish layer of sediment.
When that brownish layer is exposed as the underside of the bedding plane, it looks like this. These branching features are infilled tunnels made by marine shrimp. The walls of the tubes are ornamented by pellets placed there by the shrimp in their frenetic activity. Combining these pellets with the branching style we can place this trace fossil in the venerable ichnogenus Ophiomorpha.
This is a closer view showing the branched galleries and maybe a bit of the pitted surface showing where the pellets were attached. These tunnels are completely filled, so we refer to this preservation as full relief.
I know, I know, I should be recording the bryozoans from this stop, but they were far from photogenic!
Mark Wilson June 4th, 2013
CATANIA, SICILY, ITALY–After lunch our International Bryozoology Association field trip actually collected fossil bryozoans. We visited a quarry exposure of Lower Pleistocene cemented marls rich in the bryozoan Celleporaria palmata (Michelin), along with many other species. These were apparently from a thicket of bryozoan colonies broken up in a storm and deposited as a debris flow down slope. The location is south of Catania at Pianometa.
Lower Pleistocene Celleporaria palmata fragments at Pianometa. This was a very rapid-growing, branching bryozoan colony easily fragmented by storm currents.
Below those bryozoan-loaded beds is this unusual sequence. The darker layered units are volcaniclastic sediments derived from early eruptions from the Mount Etna complex. Occasionally boulders would roll downslope and be deposited as xenoliths (“foreign rocks”) Later the cemented sediments cracked repeatedly due to the intense earthquake activity associated with this tectonic boundary between the European and African plates. Those cracks filled with marly sediment from above.
The last visit of the day was to a sheep cheese farm. One sheep produces about a liter of sheep’s milk. The cheese we sampled (some more than others) is very soft — like cottage cheese without the lumps, or a soft ricotta. Interesting (and unpasteurized). We watched four rams beat each other bloody in an ongoing context monitored by large black dogs. I suppose it is part of the herding process, grim as it is.