Archive for June 8th, 2013

Return to the Pliocene at Altavilla Milicia, Sicily

June 8th, 2013

9. Altavilla Milicia 060813Our last stop of the day on the IBA field trip was to a classic fossil locality on the north coast of Sicily about an hour east of Palermo. These are fine sandstones and marls preserving a diverse array of mollusks from the Pliocene, including the bivalves shown below. Over 130 bryozoan species have been recorded from this site since 1921. The most interesting features to me were the numerous sclerobionts, including shallow worm and barnacle borings and encrusting bryozoans and barnacles.
10. Altavilla Milicia fossils 060813From here it was a long drive to the beautiful and ancient city of Milazzo to prepare for our last day of the field trip.

A Phoenician island city and its lagoon

June 8th, 2013

1. Mozia south harbor 060813MILAZZO, 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.

2. Mozia Museum 060813There 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.

3. Necropolis Mozia 060813Mozia has a considerable necropolis, as you would imagine. Many of the best sarcophagi and other memorial stones are in the museum.

4. Mask Mozia 060813There 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.

5. Burned guardhouse Mozia 060813Greeks 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.

6. Greek attack Mozia 060813The island museum has a diorama depicting the final breaching of Mozia’s walls by the Greeks in 397 BCE.

7. Lagoon 060813The 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.

8. Lagoon salt ponds 060813

George Davis (’64), meet Tricia Hall (’14)

June 8th, 2013

EPHRAIM, UTAH — Generations of Wooster geologists were united today over a common interest:  deformation bands of Utah!!

George Davis (Regents Professor Emeritus and Provost Emeritus, University of Arizona) researched the deformation bands of the Colorado Plateau region of Utah and wrote several very detailed manuscripts.  As we work on a structural analysis of the Sixmile Canyon Formation, we have been using two of his publications rather extensively this past week:  “Structural Geology of the Colorado Plateau Region of Southern Utah, with Special Emphasis of Deformation Bands”…and…”Conjugate Riedel Deformation Band Shear Zones”.

I actually thought that it was a unique twist of fate that Tricia and I were pouring over two of George’s publications last night…and putting our knowledge into use today in the field.

DSC00261_585

Above is a view of the Sixmile Canyon Formation, the focus of Tricia’s study.  It contains wonderful deformation bands and joints, and it just happens to be located next to two characteristic antithetic normal faults that cut the Wasatch Plateau.

DSC00291_585

Tricia and I stumbled upon these deformation bands early in the morning…

DSC00299_585

…and these later in the afternoon.  With all of the deformation bands in the area, we felt like “measuring machines”.  Indeed, we could have used help in the field today from fellow Brunton-lovers!!

In addition to looking for conjugate deformation bands that George describes from his work in southern Utah, we were also trying to identify characteristic “ladder structures” that he identified in the Sheets Gulch area.  Tricia is sampling the deformation bands for further thin section analyses to determine if they show any sign of cataclasis.  Ultimately, she would like to classify the deformation bands, using one of the kinematic classification schemes proposed in the literature.

DSC00334_585

Here’s Tricia gathering what she considers to be a “small” sample from a prominent deformation band.  You can tell how excited she is about her I.S.!!

DSC00245_585

One characteristic of this part of the Sixmile is the interesting iron “concretions” that are everywhere.  The photo above shows how abundant that they can be within the unit.

DSC00236_585

Aren’t these awesome??!!  These iron “chimneys” rise right out of the rock.  Tricia and I will be further investigating the abundance of morphologies of these concretions tomorrow, as we try to tackle some interesting paleo-fluid fronts within the Sixmile.  The past two days have been rather safe in the field, because we saw few mountain lion prints at our localities.  But, tomorrow is another day, and we are hiking back up to the areas where we saw extensive mountain lion “trace fossils”.