A geological obstacle course in Ada Canyon, southern Israel

March 19th, 2016

1 Ada canyon startMITZPE RAMON, ISRAEL — As part of our Shabbat trip today, Yoav Avni wanted to take me up Ada Canyon (N30.32973°, E34.91417°) to explore the Hazeva (Miocene) and Arava (Pleistocene). He cryptically said, “There will be places we can barely get through”. True, that. Above is Yoav at the start of the hike. Turns out this is a slot canyon with challenges.

2 Arava narrows begin“The narrow part begins”, he says helpfully.

3 Narrowing AravaAt this point I have to take off my pack to reduce my sideways width.

4 Narrow AravaAnd sideways with a twist is the only way through as the walls close in. Pro tip: Never do this when it is raining.

5 Problematic Arava sectionNow it gets problematic with boulder scrambling and claustrophobia.

6 First ladder aravaA ladder! I never did mention my aching shoulder.

7 Second ladder AravaSteps cut in the rock and then a second ladder. Going down is always easier than going up, right?

8 Rope climb AravaA knotted rope to climb the cliff! Note the shadow of successful me at the top of the last obstacle. Wondering, though, what these climbs are like on the way back.

9 Ada view 031916The view at the top of the mountain, though, really was spectacular. This is a view towards Be’er Ada, with the fault described in the previous post running diagonally across the background.

10 Hazeva cobbles 585And yes, the geology along the way! It was very impressive. The Hazeva Formation is mostly sandstone with some layers of sandy conglomerate as in the above image. It was deposited in a wetlands with occasional floods (which produced the coarse layers). The cobbles are rounded cherts derived from Jordan to the east.

11 Arava faciesThe Arava Formation was deposited in a desert much like what we see today. It is interbedded gravels (from wadis) and unconsolidated silts (from playas and saline lakes). Classic sed/strat material. It was all well worth the adventure for this aging geologist!

 

A Shabbat trip to Be’er Ada in the southern Negev

March 19th, 2016

1 Road to Beer AdaMITZPE RAMON, ISRAEL — Yoav Avni and I have a tradition on Shabbat. We drive somewhere to explore interesting geology and history unconnected to current projects. It’s not really work — it’s geotourism. We are, though, always talking about new ideas. Today we traveled south of Mitzpe Ramon into the “deep desert” of the Arava below the Negev Highlands.

2 MR view to JordanThe morning view south across Makhtesh Ramon was spectacular. It isn’t conveyed very well through an image only 585 pixels wide, but it is a perspective of unusual clarity. The purple streak at the top represents mountains in western Jordan. The haze just below them is in the Arava Valley. We are looking across most of the Negev.

3 Acacia grove Beer AdaOur mission today was to visit Be’er Ada (Bir Abu ‘Auda), an historic well, and the geology around it. (N30.32229°, E34.90701°, if you’re following at home.) The top image on this post is a view from the road to the well. Just above is a grove of acacia trees near the well. The abundance of these trees, and their good health, is an indication of accessible water.

4 Yoav at Beer AdaHere is Yoav peering down into Be’er Ada. (“Be’er” means well.) It is at least twenty meters deep. The base is filled with silt, so it will have to be dug out to supply water again. This well is thousands of years old and has been a critical watering spot in the Negev for traveling groups. The next nearest well is to the east about 40 km away. Another 40 km or so to the west is another well. Be’er Ada was active as late as the 1950s, and likely had sporadic use afterwards. The water here accumulates on the impermeable clays of the Taqiya Formation (Paleocene).

5 Acacia outcrop view 031916This is a view from near Be’er Ada to the main geological interest for me: the the orangish Hazeva Formation (Miocene) topped unconformably by the gray Pleistocene Arava Formation. We will spend much more intimate time with these units in the next post. Note the graceful acacia trees.

6 Beer Ada faultThis area is next to a complex fault system. On the left is a down-dropped block of Hazeva and Arava, with Cretaceous rocks on the right. The fault is also part of the reason for the subterranean water resources at Be’er Ada.

7 Ada profileIn the middle of the image is an example of the pareidolia so common in stark landscapes. Some people see a face in profile. Apparently tour guides like to call this the head of “Ada” for whom the well was named. However, there never was such a woman!

Note the excellent weather in these images. A perfect Negev day! Thank you to Yoav for being such a generous host.

Wooster’s Fossil of the Week: A Pleistocene octocoral holdfast from Sicily

February 6th, 2015

OctocoralHoldfastPleistoceneSicilyMy Italian colleague Agostina Vertino collected this beautiful specimen from the Pleistocene of Sicily and brought it to Wooster when she visited five years ago. It is the attaching base (holdfast) of the octocoral Keratoisis peloritana (Sequenza 1864). Octocorals (Subclass Octocorallia of the Class Anthozoa) are sometimes called “soft corals” because of their organic-rich, flexible skeletons. They are distinguished by polyps with eight tentacles, each of which is pinnate (feathery). Octocorals include beautiful sea fans and sea whips that require a hard substrate for stability. This particular holdfast is on a small slab of limestone.

The genus Keratoisis is known as the “bamboo coral” because it looks jointed like stalks of the plant. I collected fragments of Pleistocene Keratoisis branches during my visit to Sicily last year.
Giuseppe SeguenzaGiuseppe Seguenza (1833-1889) named the species Keratoisis peloritana. He was a Sicilian natural historian with broad interests, especially in geology. Although educated as a pharmacist, he found geology much more exciting on the volcanically active islands of the Mediterranean. He eventually became a professor of geology at the University of Messina (where the bust of him shown above resides). Italian sources say Seguenza received the famous Wollaston Medal from the Geological Society of London, but that does not appear to be true. Instead it appears that he was given “the balance of the proceeds of the Wollaston Fund” as a donation at the time the medal was awarded to Thomas Huxley (in 1876). The records of the society say that “the stipend of an Italian professor was too small to enable him to prosecute his palaeontological researches as fully as he could desire” (Woodward, 1876). Giuseppe Seguenza died in Messina at 56 years old.

References:

Di Geronimo, I., Messina, C., Rosso, A., Sanfilippo, R., Sciuto, F., and Vertino, A. 2005. Enhanced biodiversity in the deep: Early Pleistocene coral communities from southern Italy. In: Cold-Water Corals and Ecosystems, p. 61-86. Springer: Berlin, Heidelberg.

Fois, E. 1990. Stratigraphy and palaeogeography of the Capo Milazzo area (NE Sicily, Italy): clues to the evolution of the southern margin of the Tyrrhenian Basin during the Neogene. Palaeogeography, Palaeoclimatology, Palaeoecology 78: 87-108.

Langer M. 1989. The holdfast internodes and sclerites of Keratoisis melitensis Goldfuss 1826 Octocorallia in the Pliocene foraminifera marl Trubi of Milazzo Sicily Italy. Palaeontologische Zeitschrift 63: 15-24.

Woodward, H. 1876. Reports and proceedings, Geological Society of London. Geological Magazine 13: 181-182.

Wooster’s Fossil of the Week: Glyptodon carapace fragment from the Pleistocene

December 29th, 2013

Glyptodon carapace fragment Pleistocene 585This is a tiny bit of a large and fascinating Pleistocene animal from Central and South America. It is Glyptodon, an impressively large mammal with bony armor much like its cousin the armadillo. The above fossil is a fragment of that carapace. Each roundel is called a scute.
Glyptodon carapace side 585This is a side view of the above carapace fragment showing its thickness and layered, bony nature.
Glyptodon ReconstructionThis modern reconstruction of Glyptodon (from Wikipedia with a GNU free documentation license) shows its primary features, including the bony shell (the size and shape of a Volkswagen Beatle, as is often stated) and its characteristically large claws. It belongs to the Superorder Xenarthra, which includes armadillos, sloths and anteaters. I see the resemblance. They could not completely go turtle, as it were, but it could pull its head back enough into the shell that the scutes on the top of the skull would protect it like a cap. They had massive jaws and flat grinding teeth typical of a large herbivore. Its squat skeleton had a variety of features to support the heavy shell, including fused vertebrae and elephant-like short, stout limbs. They went extinct only about 10,000 years ago, possibly having been hunted to oblivion by early Americans. There is even some evidence that people used their empty shells as shelters.
Richard_OwenGlyptodon was formally named as a genus in 1839 by the extraordinary Sir Richard Owen (1804-1892). Owen was a giant of natural history through most of the 19th Century. He is most remembered for inventing the term Dinosauria (“terrible lizards”) and for being on the wrong side of history at the beginning of the Darwinian Revolution. He was apparently ambitious to the point of severity, and very tough on his contemporary scientists. Thomas Henry Huxley, for example, despised Owen for his treatment of his colleagues. Ironically, Huxley did considerable work on further describing Glyptodon in 1865. Owen had vision as well as sharp observational skills. He was a primary force in the eventual establishment of the Natural History Museum in London in 1881. It can be argued that this museum set the high standards of accessibility and research we now expect from all such institutions. Sir Richard Owen is such a large and well known figure I can simply refer you to one of many websites describing Owen’s life and contributions.

This post marks three complete years of Wooster’s Fossil of the Week. That’s 156 posts. You can visit the very first post (about a Devonian tabulate coral) and see how the entries have evolved, so to speak. We still have plenty more fossils to describe!

References:

Gallo, V., Avilla, L.S., Pereira, R.C. and Absolon, B.A. 2013. Distributional patterns of herbivore megamammals during the Late Pleistocene of South America. Anais da Academia Brasileira de Ciências 85(2): 533-546.

Huxley, T.H. 1865. On the osteology of the genus Glyptodon. Philosophical Transactions of the Royal Society of London 155: 31-70.

Oliveira, É.V., Porpino, K.O. and Barreto, A.F. 2010. On the presence of Glyptotherium in the Late Pleistocene of northeastern Brazil, and the status of “Glyptodon” and “Chlamydotherium“. Paleobiogeographic implications. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen 258(3): 353-363.

Owen, R. 1839. Description of a tooth and part of the skeleton of the Glyptodon, a large quadruped of the edentate order, to which belongs the tessellated bony armor figured by Mr. Clift in his memoir on the remains of the Megatherium, brought to England by Sir Woodbine Parish. FGS Proceedings of the Geological Society of London 3: 108-113.

Wooster’s Fossils of the Week: Bits of a bamboo coral from the Lower Pleistocene of Sicily

October 27th, 2013

Keratoisis melitensis (Goldfuss, 1826) 585Earlier this summer I participated on a pre-conference field trip of the International Bryozoology Association throughout Sicily. We had an excellent time and saw many wondrous things. At one stop on the western side of the Milazzo Peninsula in the northwestern part of the island we collected fossils from a fascinating foraminiferal ooze deposit known as the “Yellow Calcareous Marls” (Gelasian, Lower Pleistocene). Among the fossils in this unit were the objects pictured above. They looked like finger bones at first, but are actually the internodes (calcitic skeletal elements) of an octocoral known as “bamboo coral“. This particular species is Keratoisis melitensis (Goldfuss, 1826). I’ve never seen this group before in the fossil record. (Note, by the way, that these specimens are encrusted by foraminiferans and octocoral holdfasts. This means they rolled around on the seafloor for an extended period before burial.)
ModernBambooCoralBamboo coral belongs to the octocoral group and is only a distant relative of reef-forming “hard corals” or scleractinians. They are common today in deep seas because they do not need sunlight for photosynthetic symbionts like most hard corals do. They have multiple polyps for feeding, none of which can retract back into the skeleton. That is why the surface of these internodes is so smooth and without the usual corallite holes. Above is a colony of white bamboo coral (Keratoisis flexibilis); image from Wikimedia Commons.
bamboo_coral_585Here we have a dried specimen of Keratoisis from the Florida Straits. You can see the white calcitic internodes of the skeleton separated from each other by the black nodes made of an organic material called gorgonin. This explains why our fossil specimens consist entirely of the isolated internodes — the chitinous parts did not survive fossilization. (Image from NOAA.)

Bamboo corals are long-lived, and it has been recently discovered that they incorporate trace elements in their skeletons as they grow, making them excellent specimens for studying changes in the chemistry and circulation of deep-sea waters. These fossils may thus someday be useful for sorting out the complex changes in the Mediterranean during the Pleistocene.

References:

Langer M. 1989. The holdfast internodes and sclerites of Keratoisis melitensis Goldfuss 1826 Octocorallia in the Pliocene foraminifera marl Trubi of Milazzo Sicily Italy. Palaeontologische Zeitschrift 63: 15-24.

Sinclair, D.J., Williams, B., Allard, G., Ghaleb, B., Fallon, S., Ross, S.W. and Risk, M. 2011. Reproducibility of trace element profiles in a specimen of the deep-water bamboo coral Keratoisis sp. Geochimica et Cosmochimica Acta 75: 5101-5121.

Wooster’s Fossils of the Week: An ancient predator/prey system from the Lower Pleistocene of Sicily

September 15th, 2013

Bored and Borer for FOTWThe above fossils were collected from a Lower Pleistocene silty marl exposed near the Megara archaeological site east of Augusta, Sicily, Italy. I was on that epic International Bryozoology Association field trip this summer I’ve been blogging about. The shells in this locality are very abundant with hundreds of species represented, from foraminiferans to shark teeth. I thought this little vignette of a predator and its typical prey was worth noting.

On the far right is a naticid gastropod (moon snail). These mollusks are predators who kill and consume their prey by drilling holes into their shells with a specialized radula (a kind of tooth-bearing “tongue”). Their holes are distinctively beveled, with a wider portion on the outside narrowing to a smaller inner opening. The three organisms on the left all show boreholes indicating that they were likely killed and eaten by a naticid.

Or at least that’s the traditional story. A paper came out this year (Gorzelak et al., 2013) comparing predatory drill holes in shells with holes produced by physical abrasion by experimental tumbling. The sizes, shapes and locations of these abrasion-produced holes are shockingly similar to those made by drilling predators. It looks like we must be careful which holes we assign to predation and which were produced by other means.

As I look at the three victims above, two of them (the high-spired turritellid gastropod on the far left and the bivalve second from the right) have nicely beveled holes with almost perfectly circular shapes. The gastropod shell that is second from the left, though, presents problems. First, it has two holes that completely penetrate the shell. Predators occasionally bore a shell twice, but not very often. Second the holes are more irregular in shape and don’t have a noticeable beveling. This could be a feature of the thinner shell of this gastropod not recording the usual naticid boring evidence, or it could be the result of physical abrasion and not predation. It is a difficult call but an important one to those plotting the evolution of this predator/prey system through time.

References:

Gorzelak, P., Salamon, M.A., Trzęsiok, D. and Niedźwiedzki, R. 2013. Drill holes and predation traces versus abrasion-induced artifacts revealed by tumbling experiments. PLoS ONE 8(3): e58528. doi:10.1371/journal.pone.0058528

Kelley, P.H. and Hansen, T.A. 2006. Comparisons of class- and lower taxon-level patterns in naticid gastropod predation, Cretaceous to Pleistocene of the US Coastal Plain. Palaeogeography, Palaeoclimatology, Palaeoecology 236: 302–320.

Kowalewski, M., Dulai, A. and Fürsich, F.T. 1998. A fossil record full of holes: The Phanerozoic history of drilling predation. Geology 26: 1091–1094.

Tyler, C.L. and Schiffbauer, J.D. 2012. The fidelity of microstructural drilling predation traces to gastropod radula morphology: paleoecological applications. Palaios 27: 658–666.

Wooster’s Fossils of the Week: A foraminiferal ooze from the Pleistocene of Italy

August 18th, 2013

YCM forams 1On a recent field trip to Sicily, our paleontological party visited outcrops at Cala Sant’Antonino on the western side of the Milazzo Peninsula in the northwestern part of the island. We saw there an Early Pleistocene sedimentary unit informally called the “Yellow Calcareous Marls”. With a handlens you would see a close view of the rock like the image above. It consists almost entirely of tiny hollow white spheres with occasional dark flecks. In the lab back home these little calcitic balls were revealed to be tests (skeletons) of foraminiferans known as Globorotalia inflata (d’Orbigny, 1839). This is a classic example of a biogenic sediment called foraminiferal ooze, samples of which are now in Wooster’s paleontological and sedimentological teaching collections.
Foram-Marl-060913This is the outcrop of the “Yellow Calcareous Marls” at Cala Sant’Antonino from which the above samples were collected. The rock is very soft and powdery to the touch.

YCM forams 2In this closer view of the rock the individual foraminiferal tests are more apparent. Near the center is one example showing the connected bulbous chambers (making it multilocular) and the slit-like aperture between them. These tests are slightly recrystallized, giving them a sugary look. The dark bits are sand-sized volcaniclastic grains derived from early eruptions of the Mount Etna complex.

Globorotalia_inflataThese are modern examples of Globorotalia inflata. (The scale bars are 0.1 mm.) The bumpy surface texture, bulbous chambers and distinctive aperture make identification of the fossil examples fairly easy. The images were taken by Bruce Hayward.

Globorotalia inflata is a long-lived planktonic species, meaning it floats about near the top of the water column throughout the oceans. In life these single-celled organisms extend thin strands of material (pseudopodia) into the water around them to collect organic material and the occasional diatom or radiolarian for nutrition. They live in populations with billions of individuals, so under the right conditions their tests can accumulate on the seafloor in numbers so vast they form thick deposits, our foraminiferal oozes. Our particular ooze in this story formed in relatively deep (epibathyal), cool waters during one of the early glacial intervals. This foraminiferan turns out to be a critical guide to the age of the unit as well as its paleoenvironmental context.

References:

Fois, E. 1990. Stratigraphy and palaeogeography of the Capo Milazzo area (NE Sicily, Italy): clues to the evolution of the southern margin of the Tyrrhenian Basin during the Neogene. Palaeogeography, Palaeoclimatology, Palaeoecology 78: 87–108.

Sciuto, F. 2012. Bythocythere solisdeus n. sp. and Cytheropteron eleonorae n. sp. (Crustacea, Ostracoda) from the Early Pleistocene bathyal sediments of Cape Milazzo (NE, Sicily). Geosciences 2012 2: 147-156.

 

Limestones, basalts, the wine-dark sea and the brooding volcano

June 16th, 2013

1.BasaltLimestone061613CATANIA, SICILY, ITALY–Today we had our last field trip associated with the 2013 International Bryozoology Conference. We traveled to the east coast of Sicily at Castelluccio, which is south of Catania and north of Syracuse. The weather could not have been better. It was, as a commenter has said, “impossibly beautiful”.

The view above is of Early Pleistocene limestones resting on tholeitic basalt flows. As our guides said, in this place we could see the interplay of extensional tectonics, regional uplift, and glacially-controlled sea-level changes. The visuals were stunning. In the background you can see the east flank of Mount Etna.
2.Thalassinoides061613The limestones were of shallow-water origin and very diverse. One layer was almost completed bioturbated (biologically stirred up) by crustaceans, producing a trace fossil of connected tunnels called Thalassinoides.
3.FossilScallops061613Fossils were abundant in some units. Here is an horizon rich in scallop shells. These shells are often preferentially preserved because they are made of hardy calcite rather than chemically unstable aragonite like most other mollusk skeletons.
5.Dike061613The interactions between the basalt flows and the calcareous sediments were fascinated. Above you see a black basaltic dike cutting vertically through the limestones. Why there are no visible baked zones is a mystery to me.
4.BakedZone061613In this image we have basalt above and sediments below. The pink color of the limestones tells us they were cooked by the hot lava that flowed over them.
6.Beachrock061613There are a variety of post-depositional geological processes operating at this outcrop. One of them is the superimposition of beachrock during sea-level highstands. Beachrock is a cemented sediment formed in the surf zone by precipitation of carbonate. This particular beachrock was plastered onto an eroded limestone cliff like stucco. You can see black basalt among the diverse clasts.
7.EtnaBayView061613Over it all rules Mount Etna, here viewed from the top of the outcrop. It was unusually smoky today, which does not show well in our photographs because of the murky haze. We headed to this behemoth for the second and last stop of our field trip.

A shelly bonanza from the Pleistocene of Sicily

June 5th, 2013

5. MegaraDitch060513NOTO, 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.

6. AndrejMegara060513Colleague Andrej Ernst is examining a layer of shells extending the length of the drainage ditch.

7. SerpulidsMegara060513Her 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.

7a. TurritellidsMegara060513Turritellid 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.

8. HornedQuadrupedsMegara060513This 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!)

 

Sicilian fossils at last!

June 4th, 2013

FieldStopOne060413CATANIA, 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.

Celleraria060413Lower Pleistocene Celleporaria palmata fragments at Pianometa. This was a very rapid-growing, branching bryozoan colony easily fragmented by storm currents.

Volcaniclastic060413Below 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.

SheepCheeseFarm060413The 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.

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