A Wooster Geologist is finally warm enough

April 7th, 2014

Yoav Zichor 040714MITZPE RAMON, ISRAEL–When I left Wooster on Saturday morning it was 34°F and overcast. It was sunny and an astonishing 84°F when I arrived in Tel Aviv on Sunday afternoon. That additional 50 degrees felt very good indeed after a winter of polar vortices and late-March snowstorms. I’m now based in the Ramon Suites Hotel in Mitzpe Ramon near the lip of the spectacular Makhtesh Ramon (N 30.60638°, E 34.80128°).

I’m back in Israel as part of my research leave from the College. This is my chance to explore new outcrops and ideas with my Israeli colleagues to prepare for the next generation of Independent Study students — and, of course, to do plenty of science for its own sake. I miss my students, though, for their companionship, sharp eyes, challenging questions, and navigation abilities (i.e., telling me when I’ve taken a wrong turn). This is how the leave system works so that we always have fresh projects with interesting and testable hypotheses. This is my 11th field season in Israel.

Today I met my long-time friend Yoav Avni of the Geological Survey of Israel, along with Zeev Lewy, a paleontologist retired from the Survey, to look at a fossiliferous unit Zeev discovered over two decades ago south of Mitzpe Ramon. We looked at the thickest section of the Zichor Formation (Late Cretaceous, Coniacian) to sort out a remarkably diverse set of silicified (silica-replaced) fossils associated with a mat of worm tubes (possibly of the genus Filograna). The top image shows the upper portion of the Zichor, with Yoav for scale (location: N 30.30587°, E 34.96543°). The image below is a view of the bedding plane with most (but not all) of the silicified fossils colored dark brown.

Zichor silcified fossils 040714One of the cool things about this layer is that the fossils are silicified, which is rare in this part of the Cretaceous section. Another is that aragonitic mollusks are preserved in this way (especially gastropods and bivalves), along with their calcitic cousins (like oysters and pectenids). The Filograna-like worm tube layer itself is fascinating since no one knows much about the paleoecology of this group, and we suspect it may have some significant evidence about the paleoenvironment encoded in its spaghetti-like appearance.

Zichor Menuha contact 040714The top of the Zichor meets the bottom of the Menuha Formation chalks (Late Cretaceous, Santonian). In this view, the yellow and brown Zichor is in the foreground and middle ground, with the whitish Menuha in the background.

Zichor Menuha close 040714Yoav and I visited the boundary between the Zichor (darker unit on the left) and Menuha (lighter on the right) to assess their relationship (N 30.30212°, E 34.95909°). At outcrops 30 km to the north this boundary is marked by a deep unconformity (eroded interval) and a layer of encrusted and bored cobbles. Here the boundary is flat and nearly continuous. The layer of silicified shells is just a few centimeters below the unconformity. This may not be by chance — units immediately below unconformities often have silicified zones.

Some of you may remember these unit names from previous expeditions. Micah Risacher (’11) worked on the Zichor Formation and its fossils in the Makhtesh Ramon area, and Andrew Retzler (’11) did his Independent Study research on the Menuha. We can now build on their excellent work as we develop additional outcrops and new questions.

Ordnance 040714Finally, it wouldn’t be the Negev if there wasn’t some ordnance on the outcrop. Can you tell what kind of bomb is shown above? The clues are in its current condition!

Wooster’s Fossils of the Week: Trace fossils making ghostly shells (Upper Cretaceous of Mississippi)

January 26th, 2014

Entobia gastropod Prairie Bluff Chalk FormationThe unusual fossil above was collected by Megan Innis (’11) and myself in Mississippi during a May 2010 paleontological expedition with Caroline Sogot and Paul Taylor of The Natural History Museum, London. That splendid trip has contributed already to one high profile publication (Sogot et al., 2013) and no doubt more will come from the excellent collections we made. All the fossils in this post came from the Prairie Bluff Chalk Formation (Maastrichtian) exposed at the intersection between Highway 25 and Reed Road in Starkville, Mississippi (locality C/W-395).

The specimen is a marine gastropod (fancy name for a snail), which is hard to believe considering no shell is preserved. The shape of the original aragonitic shell has been taken by a series of interlocking blobs, each with a sediment-filled tube extending outwards. These are casts of chambers made by a boring clionaid sponge. The resulting trace fossil is known as Entobia, a form we have seen several times in this blog. The sequence of events: (1) The sponges excavated cavities connected by tunnels into the aragonite shell of the gastropod, maintaining connections to the seawater for filter-feeding; (2) the cavities and tubes filled with fine-grained calcareous sediment after the death of the sponges; (3) the aragonite gastropod shell dissolved away, probably at the same time the sediment filling the cavities was cemented; (4) the fossil was exhumed as a series of natural casts of the sponge cavities — the trace fossil Entobia.
Entobia bivalve 1 exterior Prairie Bluff Chalk FormationThere were many other such fossil ghosts at this locality, such as the apparent bivalve shell fragment above.
Entobia cast close Prairie Bluff Chalk FormationIn this closer view (taken with my new extension tubes on the camera) we see some of the interlocking sponge chamber casts. On the surfaces of some you can just make out a reticulate pattern that represents tiny scoop-like excavations by the sponges. In the upwards-extending tubes there are a few green grains of the marine mineral glauconite.

As a paleontologist it is always sobering to see a fossil preserved in such an odd way. Were it not for these circumstances of boring, filling and cementation, the shells would have completely disappeared from the fossil record. Every fossil we have, really, is a victory of improbable preservation.

References:

Bromley, R.G. 1970. Borings as trace fossils and Entobia cretacea Portlock, as an example. Geological Journal, Special Issue 3: 49–90.

Schönberg, C.H. and Shields, G. 2008. Micro-computed tomography for studies on Entobia: transparent substrate versus modern technology, p. 147-164. In: Current Developments in Bioerosion. Springer; Berlin, Heidelberg.

Sogot, C.E., Harper, E.M. and Taylor, P.D. 2013. Biogeographical and ecological patterns in bryozoans across the Cretaceous-Paleogene boundary: Implications for the phytoplankton collapse hypothesis. Geology 41: 631-634.

Sohl, N.F. 1960. Archeogastropoda, Mesogastropoda, and stratigraphy of the Ripley, Owl Creek, and Prairie Bluff Formations, p. A1-A151. In: Late Cretaceous gastropods in Tennessee and Mississippi: U.S. Geological Survey Professional Paper 331-A.

Taylor, P.D. and Wilson, M.A. 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62: 1-103.

Wilson, M.A. 2007. Macroborings and the evolution of bioerosion, p. 356-367. In: Miller, W. III (ed.), Trace Fossils: Concepts, Problems, Prospects. Elsevier, Amsterdam, 611 pages.

First Wooster geology presentation at the 2013 annual meeting of the Geological Society of America in Denver, Colorado

October 27th, 2013

Oscar102713DENVER, COLORADO–It’s that time of year for geologists when we collect at one of two major national meetings. Wooster geologists are always well represented at the Geological Society of America convention, this year held in downtown Denver. Meagen Pollock, Shelley Judge and I are here with nine enthusiastic Wooster students. Some events have already taken place (notably for me the paleontology short course and an epic annual banquet meeting of the Paleontological Society), and we’ve had our first student poster presentation.

Oscar Mmari is shown above with his poster entitled: “Syndepositional faulting, shallowing and intraformational conglomerates in the Mishash Formation (Upper Cretaceous, Campanian) at Wadi Hawarim, southern Israel“. Readers of this blog will remember Oscar’s summer work in the Negev measuring and describing sections. Oscar’s presentation went very well. Every time I stopped by the poster someone was in deep conversation with him.

CCC102813Here’s an early morning view of the Colorado Convention Center in Denver where we’re doing our work and study (and socializing, truth be told). The weather this weekend has been fantastic, but a big change will come tomorrow morning.

More posts will follow!

Wooster’s Fossils of the Week: Dinosaur teeth from the Cretaceous of Morocco

July 21st, 2013

Spinosaurus_aegyptiacus_Cenomanian_Alnif_Morocco_Tooth_052013The fossil above is the best of a collection of dinosaur teeth given to us by the generous George Chambers (’79). The species that held it is the gargantuan theropod predator Spinosaurus aegyptiacus Stromer, 1915. The teeth are from Cenomanian (Upper Cretaceous) rocks exposed near Alnif, Morocco.
Spinosaurus_Group052013Here are some more of our Spinosaurus aegyptiacus tooth collection. You can see that the teeth have been extensively repaired with plaster and epoxy. That’s fine for us because they’re the only dinosaur teeth we have!

(Reconstruction by Dimitry Bogdanov, Wikipedia)

(Reconstruction by Dimitry Bogdanov, Wikipedia)

Spinosaurus is surprisingly little known in the general public, at least until the Discovery Channel started making incredible videos about the extinct beast. It was the largest of all carnivorous dinosaurs yet discovered — even bigger than Tyrannosaurus, Allosaurus and Gigantosaurus. Some specimens were up to 18 meters long. Spinosaurus was characterized by long spines extending up from the vertebrae almost like a pelycosaur. Its head was like that of a crocodile — long and narrow. Its teeth, too, are like those of crocodiles and alligators, being blunt, rounded and strong rather than sleek and sharp. They probably crushed and shook their prey in a crocodilian way as shown in those amazing Discovery Channel videos.

The original specimen of Spinosaurus was discovered in Egypt in 1912. Those fossils were completely destroyed when Munich, Germany, was bombed in 1944 by the Royal Air Force. Since then a few other incomplete skeletons have been found, along with lots of teeth.
435px-Ernst_StromerSpinosaurus was found, described and named by Ernst Freiherr Stromer von Reichenbach (1870-1952), a German paleontologist and aristocrat. Stromer’s scientific odyssey is worthy of a movie and is the basis of an excellent book (The Lost Dinosaurs of Egypt). He began his paleontological work in Egypt in 1910 at a time tensions between the British and Germans were ramping up. He fought disease, weather extremes and bureaucratic delays to make his unexpected dinosaur discoveries. As just one example, his fossils actually arrived in Germany in 1922 — ten years after they were collected. (World War I only took up four of those years.) In his latter years he refused to join the Nazi Party and maintained relationships with Jewish friends. This may have led to the destruction of the Spinosaurus specimens because the Nazi director of the Munich museum refused to move the fossils to a safe location. In the end he outlived the Kaiser and the Führer, dying at the age of 82 in 1950. A tough paleontologist in a tough time.

References:

Amiot, R., Buffetaut, E., Lécuyer, C., Wang, X., Boudad, L., Ding, Z., … and Zhou, Z. 2010. Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods. Geology 38: 139-142.

Buffetaut, E. and Ouaja, M. 2002. A new specimen of Spinosaurus (Dinosauria, Theropoda) from the Lower Cretaceous of Tunisia, with remarks on the evolutionary history of the Spinosauridae. Bulletin de la Société géologique de France 173: 415-421.

Nothdurft, W. and Smith, J. 2002. The Lost Dinosaurs of Egypt. Random House, 242 pages.

Smith, J.B., Lamanna, M.C., Mayr, H. and Lacovara, K.J. 2006. New information regarding the holotype of Spinosaurus aegyptiacus Stromer, 1915. Journal of Paleontology 80: 400-406.

Last day of fieldwork for Team Israel 2013

July 11th, 2013

1_DragFoldOscar071113MITZPE RAMON, ISRAEL–We like to think that Dr. Shelley Judge would be proud of our fieldwork today. The Wooster Geologists returned to Wadi Hawarim to finish our fieldwork for Oscar Mmari’s project on synsedimentary faulting in the Mishash Formation (Campanian, Upper Cretaceous). We returned to the fault visible above just to the left of the dark outcrop of the lower Mishash. The left side is upthrown, the right downthrown, making this a very steep normal fault. the Mishash seen here is in a magnificent drag fold against the fault. The Mishash is eroded away on the upthrown block, so we could only climb to the top of the hill here and estimate the minimum displacement on the fault. The blocks are separated by at least 50 meters. The fault trace is almost exactly east-west. You can barely see Oscar in the lower right standing on the spot where the Mishash rocks fold more than 90° to become horizontal to the right. Oscar and I worked today to follow the fate of a conglomerate that is thickest at the fault where Oscar is standing (location 031 on the image at the end of this post), and then thins and becomes finer as we move away from the fault into the syncline to the south. We believe this indicates that the conglomerate came from the upthrown block and thus the fault formed while the Mishash was being deposited. (Lizzie Reinthal and Steph Bosch, in the meantime, collected more shark’s teeth for us and then explored the wadi system.)

2_HawarimPhosphorites071113This is the Mishash Formation phosphorite zone several hundred meters south of the fault (location 049 in the bottom image). It is much thicker than the section near the fault (see the top photo in this entry).

3_ThinConglomerates071113The conglomerate that is a meter thick near the fault is reduced to these two lensoidal coarse sandstones that Oscar found in this southernmost outcrop. The grain size and thickness reduces dramatically as we move away from the fault.

4_WadiHawarimSection071113This beautiful Wadi Hawarim section of the phosphorites gave us our final clues as to the relationship between the fault and the conglomerate. We also have a sealevel story here with shrimp burrows, but we’ll save that for a later post after Oscar has done some lab work.

5_Hawarim071113Here is a Google Earth view of Oscar’s collecting sites and measured sections. The fault shown in the top photo is at 031, with the photo taken from 047. The fault runs east-west, and Oscar’s sites are all to the south.

 

Wooster Geologists in Jerusalem

July 10th, 2013

1_JerusalemWalls071013MITZPE RAMON, ISRAEL–This is the beautiful 400-year-old Turkish wall surrounding Jerusalem. It and virtually all the buildings in Jerusalem is made of “Jerusalem Stone” (a set of Cretaceous micritic limestones, to be pedantic). When the sun rises or sets on them they turn the city into the fabled “Jerusalem of Gold”.

Team Israel 2013 made the long drive up to Jerusalem with our colleague Yoav Avni to meet with geologists at the Geological Survey of Israel, and then visit Hebrew University and the National Natural History Collections. Of course, I also gave the students a tour of the Old City with its incredible history and multi-dimensional culture.

2_YoavOffice071013Had to show an image of Yoav in his office. Typical geologist’s office, I’d say. The Geological Survey of Israel is housed in a century-old complex built as a school by Germans and then occupied by the British Army from 1918 to 1948. It is incredibly cramped so they are moving to new facilities in a few years.

3_FossilSnake071013We saw many, many fossils and modern bones at the National Natural History Museum collections on the campus of Hebrew University. The staff was very generous with their time, and their enthusiasm was inspiring. Our token image: a Cretaceous snake with tiny legs just barely visible.

4_StudentsChurchSepulchre071013Our journey through the Old City was so much fun, even though we had to move relatively quickly. We walked here from the Survey buildings through diverse neighborhoods and then down the newly-renovated Jaffa Street. Here you might be able to make out the three Wooster students in front of the Church of the Holy Sepulchre.

5_WesternWall071013We also went to the Western Wall of the Temple Mount complex, a treasured site in Judaism.

6_Dome071013We couldn’t visit the Temple Mount because it was closed, but we did get this excellent view of the Dome of the Rock, an iconic Islamic shrine.

7_ZionGate071013This is the outside of Zion Gate in the Jerusalem Old City walls. The innumerable bullet holes are a reminder of the violence this city has seen over the centuries. Most of these are from the War of Independence (1948-1949) and the Six-Day War (1967).

8_GroupGSI071013Finally, here is our last group photo: Steph Bosch, Lizzie Reinthal, Oscar Mmari, me, and Yoav Avni. Yoav is leaving for Jordan tomorrow so this is the last day he is with us. The photo was taken by my long-time friend, Israeli geologist Amihai Sneh.

What a day in such a place.

Return to the Ora Formation

July 9th, 2013

8_MudVolcano070913MITZPE RAMON, ISRAEL–The last location Wooster Geologists in Israel visited today was on the southern edge of the Makhtesh Ramon structure (N 30.58209°, E 34.89375°). Here are excellent exposures of the Ora Formation (Upper Cretaceous, Turonian). This curious feature was a challenge to the students to interpret. I also got it wrong in my explanation on the outcrop, so listen up Steph, Lizzie and Oscar! The students are standing in a portion of the outcrop that is mud with suspended blocks of limestone. This is a cross-section of a diapir, or body of sediment that has moved upwards through the rocks that cap it. This was caused by water-saturated sediment being compressed by the sediments above, forcing it upwards through cracks and crevices. What I got wrong was that the flat strata on top of the mud was present when the diapir formed. (I said it came later.) The mud never reached the surface to become a mud volcano. This is why the resistant beds below are bent downwards — the upward force of the mud flow was stopped by the capping rock, thus deflecting the edges of the units below. A complicated story — which is one of the many things that makes the Ora Formation interesting.

9_Oysters070913Also in the Ora Formation at this same site is a half-meter-thick unit composed entirely of oyster shells. Many of the oysters are encrusted with other oysters and, who knows, maybe bryozoans as well. (And no, Paul Taylor, I didn’t see any here yet!)

10_Hardground070913The Ora Formation also has a fabulous carbonate hardground, which was a cemented seafloor surface. We can tell this particular surface was hard rock on the Cretaceous seafloor because of all those little holes. These are the borings of bivalves known as Gastrochaenolites. They could only be made by grinding away at a cemented substrate.

Hardgrounds, oysters, odd diapirs … opportunities for future study! Israeli geologists have done fantastic work with this unit, so there are many collaborations possible here.

A day of geological exploration in the Negev: the En Yorqeam Formation (Upper Cretaceous) at Makhtesh Ramon

July 8th, 2013

12_EnYorqeamView070813MITZPE RAMON, ISRAEL–Our final stop on our geological tour today was close to our temporary home: on the northern rim of Makhtesh Ramon (N 30.62831°, E 34.81759). Exposed here is the En Yorqeam Formation (Upper Cretaceous, Cenomanian), seen above as the less resistant marly unit between two resistant limestones. I did my first presentation on Israeli geology with bored and encrusted oysters from the En Yorqeam, which were also the subjects of a Fossil of the Week post.

We visited this outcrop today because there are some stratigraphic questions about its thickness and distribution. Its rich fossil fauna has also not been described in detail. This would be an ideal Independent Study project someday, especially with one large outcrop so close to our headquarters.

13_Echinoids070813Echinoids are the stars of the fossil fauna in the En Yorqeam. In just ten minutes we picked up over a dozen well preserved specimens. The large ones at the top are Heterodiadema lybicum. I don’t know the identity of the two in the bottom row. I bet some sharp student, though, can come up with the names quickly!

An outcrop Dr. Judge would love (Upper Cretaceous of southern Israel)

July 5th, 2013

WadiHavarimDragFold070513MITZPE RAMON, ISRAEL–Wooster Geologists Oscar Mmari’s Independent Study project on the Late Cretaceous phosphorites in the Negev has become multidimensional. His most interesting section is in Wadi Hawarim, where we returned today with Yoav Avni for additional observations and measurements. We are now doing a bit of structural geology that Dr. Shelley Judge would appreciate. In this view above, the dark resistant unit on the left is the lower silicified portion of the Mishash Formation (Upper Cretaceous). Even though it looks like an igneous intrusion, these are sedimentary beds folded so that they are vertical in attitude. On the right you may be able to make out Oscar standing on Mishash beds that are almost horizontal. How does this make sense?

What happened was faulting on the farthest left in this view above. A normal fault perpendicular to this screen has its upthrown block on the left and downthrown block on the right (where Oscar is standing). The Mishash silicified rocks are part of a drag fold as the blocks moved against each other. It appears that this faulting took place while the rest of the Mishash was still accumulating because debris from the silicified layers was spread over the phosphorites as they developed. There may also have been a shallowing of sealevel indicated by a layer colonized by shrimp who made Thalassinoides burrow systems that became inundated with siliciclastic sediment likely derived from the fault scarp.

OscarWadiHavarim070513In this view into Wadi Havarim, the whitish phosphorite beds of the Mishash Formation are in the center above a dark conglomerate and below the yellowish Ghareb Formation.

OscarAtWork070513Oscar is sitting on Mishash conglomerate taking careful notes on this complex geological scenario. He’s going to need his skills in structural geology, sedimentology, stratigraphy and paleontology for this project!

Phosphate success while Jurassic bryozoans remain elusive

July 4th, 2013

OscarOZsection070413MITZPE RAMON, ISRAEL–Oscar Mmari celebrated on his second outcrop today the completion of his stratigraphic columns for his project on the phosphate-bearing portions of the Mishash Formation in the Negev of southern Israel. It is certainly the least pretty section we’ve worked with because it is in the industrialized mining zone near the eastern outlet of Makhtesh Gadol, but we got the work done. This particular place is at N 30.94072°, E 35.03784° (for those of you following along). Look at this place on Google Earth and you’ll see how extensive the phosphate mines are here. Oscar is not yet done with fieldwork because we will come back to his sections for further observations and collecting.

LizzieStephMatmor070413Later in the afternoon we visited outcrops of the Matmor Formation in the northern part of Makhtesh Gadol. Just above Lizzie Reinthal’s right shoulder above (she’s in the center) the outlet from the makhtesh is visible as a break in the surrounding walls. Steph Bosch on the right is bravely hiding her disappointment because after lots of careful peering at the encrusted undersides of beautiful fossil corals, the four of us failed to come up with a single bryozoan. This is curious in itself. The encrusters are well preserved and diverse. (Olev Vinn and I wrote a paper on the various serpulid and sabellid worm tubes; Cezary Krawczynski and I have a paper on the thecideide brachiopods from here.) Every place we think we will see bryozoans we find instead worm tubes and calcisponges. The few Matmor bryozoans collected on previous field trips have been on echinoderm ossicles and holdfasts. Since echinoderms are common where corals are not, and vice versa, it may be that the bryozoans preferred the same conditions the crinoids and echinoids did. Later on this trip we will thus have a full-court press in the crinoid thickets and echinoid-rich beds.

PrettyCorals070413Still, the corals here are gorgeous. Here are two varieties of typical colonial scleractinians we saw today. The one on the right has all sorts of encrusters in the nooks and crannies between its corallites. The corals here are remarkably well preserved considering that their original aragonitic skeletons have been replaced by calcite. These are a bit of consolation for the missing bryozoans!

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