Archive for the 'Uncategorized' Category

Wooster’s Fossil of the Week: An unusual scleractinian coral from the Upper Cretaceous of Israel

April 13th, 2014

Aspidiscus 041114aOriginally this was going to be a mystery fossil for a crowd-sourced identification while I’m here in Israel doing fieldwork, but through the wonders of the internet I finally found a match for the strange fossil above: it is the scleractinian coral Aspidiscus König, 1825 (Family Latomeandridae) Yoav Avni and I found several specimens in the lower third of the En Yorqe’am Formation (Upper Cretaceous, Cenomanian) in the Negev of southern Israel. I had never seen anything like it before.

The view above is of the upper surface of this discoidal fossil. There are several short and seemingly random ridges, which I learned later are called monticules in this genus. Each monticule has a series of septa, or thin vertical partitions. This was a compound coral, meaning it had multiple polyps on its surface, presumably each sitting on a monticule.
Aspidiscus 041114bThis is a reverse view of the En Yorqe’am variety of Aspidiscus. The pits appear to be molds of a gastropod on which the young coral must have recruited. It then grew centripetally, making a fine series of growth lines across a soft sediment.
Aspidiscus cristatus diagramThis diagram from Pandey et al. (2011) is a diagram of Aspidiscus cristatus found in the Cenomanian of Sinai, not too far from here. (This species is also found in Algeria, Tunisia, Spain, Greece, and Afghanistan — all in the Cenomanian.) Note that the center of A. cristatus has two large crossing monticules and the Israeli specimen does not. This is why I’m keeping it in open nomenclature — it doesn’t appear to be the same species. A. cristatus is found in the middle to early late Cenomanian; the En Yorqe’am specimen seems so far to be only in the early Cenomanian. This may mean the Israeli version is an older species. Both clearly liked living in marly shallow marine sediments.
Aspidiscus symbiontsHere’s the bonus: look at the round holes in the upper surfaces of these two specimens. These are caused by symbionts of some kind that lived within the growing coral. You can see best in the specimen on the right how the coral grew around the symbionts, producing a kind of tube. Nice.

Sorry for the lower quality of images this week. I’m photographing the fossils as best I can with a bedside lamp, a tiny tripod, and a shirt for background.

References:

Avnimelech, M. 1947. A new species of Aspidiscus from the Middle Cretaceous of Sinai and remarks on this genus in general. Eclogae geologicae Helvetiae 40: 294-298.

Gill, G.A. and Lafuste, J.G. 1987. Structure, repartition et signification paleogeographique d’Aspidiscus, hexacoralliaire cenomanien de la Tethys. Bulletin de la Societe Geologique de France 3: 921-934.

Pandey, D.K., Fürsich, F.T., Gameil, M. and Ayoub-Hannaa, W.S. 2011. Aspidiscus cristatus (Lamarck) from the Cenomanian sediments of Wadi Quseib, east Sinai, Egypt. Journal of the Paleontological Society of India 56: 29-37.

Wooster’s X-ray Lab Hosts Expanding Your Horizons

April 12th, 2014

WOOSTER, OH — What a beautiful Saturday for science!!  Expanding Your Horizons (EYH) hit Scovel Hall again this year, and area middle school girls were able to select “Minerals in My Jewelry” as one of the fun science sessions held around campus.  Meagen Pollock, who oversees Wooster’s X-ray Lab, organized and taught “Minerals in My Jewelry”, with assistance from others in the department:  Sarah Bender (’15), Olivia Brown (’15), Elisabeth Gresh (’15), Kaitlin Starr (’16), and Shelley Judge.  The goal of the session was to analyze common jewelry beads using Geology’s XRD in order to determine the correct mineral identification for the beads.  EYH participants then were able to compare the XRD results to actual mineral specimens from the department’s collections.  Then, they made bracelets from the beads that they identified with the XRD.

1-585EYH participants meticulously prepared jewelry bead powders for the Rigaku MiniFlex II X-ray diffractometer, or XRD.

2-585Olivia Brown (’15) oversees one group preparing their sample for the XRD.

3-585Meagen Pollock points to the resultant XRD pattern and mineral identification for a team of students.

4-585Expanding Your Horizon students were able to compare the XRD results to their jewelry beds and to hand-sample mineral specimens.  Here, the group is focused on the purple specimen of amethyst (quartz), which was one of the jewelry beads in the collection.

5-585Sarah Bender (left; ’15) and Kaitlin Starr (right; ’16) are ready to take their group’s sample to the XRD for analysis.  The students, with instruction from Meagen Pollock, actually ran the computer software that controlled and monitored the XRD.

6-585Elisabeth Gresh (right; ’15) works with another group, who is also preparing a sample.  In the background, Provost Carolyn Newton, who visited “Minerals in My Jewelry”, watches the various groups in the room.  After a few minutes of watching the students in action, Provost Newton jumped right in and participated in the activity.

8-585Toward the end of the exercise, Meagen Pollock always made sure that the students could identify all of their jewelry beads in their bracelets.  In the background, you can see that President Grant Cornwell and Peg Cornwell have just popped in for a visit.

Those of us in the department who participated in the Expanding Your Horizons sessions had a very fun day working with the middle school students interested in science, and we look forward to participating again next year!!

Seeing the archaeological site of Shivta through a geologist’s eyes

April 12th, 2014

01 Yoav Shivta 041214MITZPE RAMON, ISRAEL–The tradition we’ve built over the years on our Israel expeditions is to travel to interesting places on Saturdays to take a break from work. Yes, it appears geologists never really stop geologizing, but then that’s not really “work”, is it? Today Yoav, part of his family and I went to the Nabatean-Byzantine city of Shivta to explore the ruins and ponder the role of geology in the development of the settlement. You can find Shivta on the map at N 30.88185°, E 34.62878°. This site was studied by several archaeologists over the years, but I’m most impressed by the visit of T.E. Lawrence here in 1914. (Yes, that Lawrence.)

The questions: Why did this city develop here off the main routes? Did climate change force the abandonment of this city along with many other Negev settlements? Obviously we’re just poking around with these, but Yoav has some really good observations.

02 Shivta drainage 041214Obtaining enough water in this very dry place would have been the first problem to solve. The area has a limestone bedrock that the inhabitants could cut and carve to make many channels to direct storm rainwater into cisterns for storage and use during the dry seasons. Here we see a channel cut directly into the bedrock floor of the city plaza. At the top of the image are rock slabs covering the channel. They would have extended for the whole length to reduce evaporation.

03 Shivta cistern 041214That drainage channel, and many others, leads to this large cistern in the center of the town. It is mostly filled with sediment now. During its use it was many meters deep and had plastered walls to reduce leakage. Archaeologists have calculated that enough water could be stored in this cistern and many others through the city to support the population. This is with present rainfall amounts (about 10 cm a year). These cisterns could be easily built because about a meter below the hard limestone is a soft sandstone that can be excavated quickly.

04 Shivta quarry 041214The building stones for Shivta were obtained in the city itself and a few dozen meters away. Here is one of the ancient quarries. The limestone can be split vertically and horizontal slabs removed for use. You thus only have to cut the stone in two dimensions rather than three.

05 Southern church Shivta 041214This is the beautiful Southern Church. It has a classic Byzantine design. The interiors were made with soft Eocene limestones that could be easily smoothed and carved, while the rougher limestones were used for support out of sight. Some fragments of facing marbles, imported from Italy, can be seen in the alcoves.

06 Stones southern church 041214The stone above is fine-grained Eocene limestone suitable for carving. The stone in the background is coarser limestone. This is a portion of the Southern Church.

07 Shivta rock ceiling 041214Wood is a rare material, so the roofs were made of stone slabs laid across stone arches. Yes, you can imagine the earthquake danger!

08 Northern Church 041214The larger Northern Church is in the background here. Note the thick, sloping walls, especially on the left side.

09 Northern church buttress 041214In this closer view of the walls (and the Avni family dog, Anicha — great outdoor dog!), we see that the bulk of them are made of the rough limestones, and they were constructed to buttress the failing original walls, a smooth portion of which can be seen in the top right. These buttresses were made after earthquakes destabilized the finished walls.

10 Shivta earthquake damage 041214Yoav is pointing here to further earthquake damage to the buttresses themselves. The Shivta people lived through several earthquakes and continued to reinforce their structures.

11 Shivta garden 1 041214To the north of the city is this spectacular garden. It is an experimental plot to see if economic plants like olives, carob and pomegranates can be grown with just the local water trapped in basins in the Byzantine manner. The experiment ended years ago and the plants are doing great.

12 Shivta garden 2 041214This is a carob tree (Ceratonia siliqua), which is an important source of food and medicine throughout the Mediterranean region. Clearly it does well under these circumstances.

13 Shivta garden 3 041214These are olive trees, with a field of wildflowers beneath. With present rainfall amounts enough water can be trapped for agricultural and domestic use in Shivta. The hypothesis that some sort of desertification event (a common idea) ended these desert settlements is difficult to support when the dry conditions of today can still support the original community. It was likely economics and politics that spelled the end of Shivta, not climate change. We also see how critical the local geology was to the early inhabitants of this isolated city. They chose the location well for the agricultural and economic conditions of the time.

 

Cretaceous fieldwork around Mitzpe Ramon

April 11th, 2014

Makhtesh Ramon 041114MITZPE RAMON, ISRAEL–Today Yoav and I worked on the outskirts of his hometown. This was a field trip that began in his garden and then we wandered into the hills behind his house, eventually circling this little city to return to his house. About half the journey was along the cliff of Makhtesh Ramon, so the top image is a view from north to south. It is geologically inspiring to see this site every day.

MR larger view 041114After looking at the Avnon Formation for a bit (with its newly-found corals) and the Zafit Formation (with silicified tree trunks), we settled into our special mission to sort out stratigraphic issues of the En Yorqe’am Formation (Upper Cretaceous, Cenomanian). It was a lesson for me in how much a formation can differ in a few kilometers. I would not have recognized it from our explorations earlier this week. The above is a view of a new housing development and an excavation exposing the top part of the En Yorqe’am.

MR En Yorqe'am 041114This is a closer view of a mysterious silty dolomitic layer in the En Yorqe’am at the housing development. We’ve seen nothing quite like it in the other exposures of the unit. There is also below this what looks like a recrystallized biosparite showing the bedding associated with submarine dunes.

Calcite nodule 041114A key feature of that strange layer is the presence of these calcite-filled cavities. They appear to be formed from original anhydrite nodules, which were produced under hypersaline conditions. This is something we saw in the unit at Hamakhtesh Hagadol.

Grey layer MR 041114The solution to the stratigraphic dilemma of the En Yorqe’am is the position of what we call the “grey layer”. This means we have to examine it wherever it is, including on the edge of the makhtesh. “Like a sidewalk, but in the sky.” I wasn’t happy about our hike to that little point of rock, but it really was perfectly safe. And it was worth the effort because we found characteristic features to add to our analysis. It certainly was a fantastic view from there!

So this is where capers come from

April 11th, 2014

Capparis spinosa multiples wall 040914MITZPE RAMON, ISRAEL–Early Wednesday morning Yoav had a special mission to perform before we began our fieldwork. He had been asked by a botanist to get a sample of a new species of plant endemic to Makhtesh Ramon. The botanist needed it for a DNA study to confirm the species designation and link it to other related plants. This plant is a member of the Capparis genus, the most common species of which (Capparis spinosa) is a common site in our Negev field areas. C. spinosa is shown above growing in cracks of a limestone outcrop in Wadi Neqarot. (Remember that lifestyle!) The common names for the plant are the Thorny Caperbush or just Caperbush. This is where capers grow. Who knew? Capparis Yoav Yacov 040914Here are Yoav and Yacov looking at a specimen of the new species of Capparis. It grows only on the thin soil developed from gypsum exposures in the Triassic section of Makhtesh Ramon. This sulfate-rich sediment is very difficult for other plants to take root, so this species has some valuable adaptations to the geochemistry. Note there are very few other plants around it. The plant shows mostly dead growth from previous years, with the spring sprouting visible in the lower left. Capparis cutting 040914Yoav is cutting some sprigs for the sample. There are several other plants in the vicinity, so we’re not endangering the species! All for science.

Capparis collected 040914The cuttings of the Capparis plant.  Note the recurved spines beneath the branching points for the leaves. For some reason the botanist wanted these samples wrapped in newspaper, not placed in a plastic bag.

Capparis spinosa wadi 040914Here is Capparis spinosa in one of our wadis. It is a mostly upright bush with beautiful white flowers.

Capparis spinosa NegevA Capparis spinosa flower. Delicate and sweet-smelling. The fruit of these flowers are the capers that are harvested both in the wild and from cultivated varieties.

Capparis spinosa Western Wall 053011Now where have we seen these caper bushes before? Why in the Western Wall in Jerusalem. I’ve wondered what these are and where they come from. Turns out they are natives of the Middle East and particularly like growing in the cracks of limestone walls, either natural or artificial. Cool.

Field trip to the lesser known makhteshim at Har ‘Arif

April 10th, 2014

Har 'Arif 041014MITZPE RAMON, ISRAEL–We’ve talked a lot about makhteshim in this blog, with so much of our geological work located in Hamakhtesh Hagadol and Makhtesh Ramon. A makhtesh is essentially a breached anticline, usually with a single drainage running from it. There are two small makhteshim at Har ‘Arif that are rarely seen because it takes some effort to get to them (major dirt road challenges and a significant hike) and they are in a military area that has very limited access. The Geological Survey of Israel got permission to run a field trip up to the top of Har ‘Arif today, and I was privileged to go along. The image above is of Har ‘Arif (the peak in the middle) looking up through the axis of the larger of the two makhteshim here. Its elevation is 956 meters, and it is the ninth highest peak in Israel. It is noted for its craggy, angular top, which is unlike most other Negev mountains with their rounded or flattened outlines.

Geologist camp 041014We began the day with an early departure from Mitzpe Ramon to meet most of the team camped out near Har ‘Arif. Note as the sun rises the crew has jackets on. It was an unseasonably cool start.

Hike begins 041014The hike begins. The goal is the very tippy-top of the mountain, so lots of work ahead in this beautiful setting.

Group outcrop 041014As with any geology field trip, we stopped occasionally for lectures on the outcrops. These lectures were in Hebrew so I was a spectator. It’s funny that after awhile I could pick out what the major arguments were from the tone of voice and various hand gestures. Several participants (especially Yoav) kindly interpreted for me afterwards. We are here examining an outcrop of the Middle Triassic Raaf Formation. This is a unit low in the Triassic that is not seen elsewhere in Israel.

Ripples Gyrochorte 041014These are ripplemarks in a fine sandstone of the Gevanim Formation (Middle Triassic, Anisian). Note the trace fossils that are convex epirelief, meaning they are positive relief on the surface of the bed. They are of the ichnogenus Gyrochorte, an old friend of mine from the Jurassic of Utah.

View west Har 'Arif 041014We reached the top of the mountain after an arduous climb. The coordinates are N 30.42591°, E 34.734°. (Really, google map these numbers. I worked hard for them!) This is the view to the east looking over the Negev all the way to the mountains of Jordan. One limb of the smaller makhtesh is below.

Har 'Arif Makhtesh 041014Here is the larger of the two makhteshim, looking west from the top of Har ‘Arif. It is gorgeous. All the rocks making the floor and walls are Triassic. The ridge line in the far distance is the border with Egypt.

I’ll have more later on the abundant flowers of the Har ‘Arif area. Right now it is a much-anticipated bedtime for me!

A mission in the Cretaceous of southern Israel

April 9th, 2014

Wadi Mishar viewMITZPE RAMON, ISRAEL–Today Yoav and I set out to solve a mapping dilemma concerning the boundaries of the Upper Cretaceous (Cenomanian) En Yorqe’am Formation in the Negev and, eventually, the Judean Desert to the north. It involved a bumpy ride deep into some of the most beautiful areas of the country, and it produced all sorts of delicious paleontological and sedimentological mysteries. I’ll talk more about this trip in later entires. Since it was 12 hours and I get up at 4:00 a.m. tomorrow, this is a truncated entry!

The setting is the stratigraphy of the En Yorqe’am and its bounding units: the Hevyon Formation below and the Zafit Formation above. Our job was to examine the contacts between these units and help come up with consistent definitions that can be used throughout the region. Right now there is considerable fuzziness as to where each formation begins and ends. Above is a labeled image showing the magnificent outcrop in Wadi Mishar (taken from our studied section at N 30.54899°, E 34.98843°).

Oysters En Yorqeam 040914In the process of sharpening the definition of the En Yorqe’am, we found some magnificent fossils. There are many paleontological and sedimentological projects possible in this unit. Oysters dominate the En Yorqe’am in mot places we visited. Above is a close view of one outcrop (at N 30.65788°, E 35.08764°; Nahal Neqarot) showing that the sediment is almost entirely oyster. The shells are often beautifully bored, but strangely there are virtually no encrusters.

Stromatoporoid En Yorqeam 040914To our surprise, we found these large roundish objects that look very much like stromatoporoids (at N 30.65788°, E 35.08764°). The lack visible mamelons (or corallites, for that matter), but internally they appear to show the typical laminations and pillars of these calcareous sponges. I’ve never seen them in the Cretaceous before, which is at the end of their range. I could be wrong and these fossils are odd altered corals. Only cutting and polishing will tell.

Terebratulids En Yorqeam 040914Also unexpected was the prevalence of brachiopods in parts of the En Yorqe’am (at N 30.65788°, E 35.08764°). These are articulated terebratulid brachiopods. They look very Jurassic in their appearance, but here they are in the Upper Cretaceous.

I’m looking forward to working with Wooster students on these outcrops next year! More on the En Yorqe’am later this week.

Cretaceous echinoderms are today’s stars

April 8th, 2014

Zichor 040814MITZPE RAMON, ISRAEL–There’s a joke in the title, in case you didn’t notice! I was on my own for my second day of fieldwork in southern Israel. I revisited yesterday’s outcrops of the Upper Cretaceous (Coniacian) Zichor Formation, taking more time to plot out future section-measuring and fossil-collecting sites for students. I was also able to spend a lot of classic nose-on-the-ground time sorting out the fossils.

The outcrop above is about the top half of the Zichor Formation in this area (N 30.30587°, E 34.96543°). Note the cemented limestones near the top and the soft marls in the foreground. Both have plenty of fossils, but you can imagine which is easier to collect from.

Filograna? 040814One mystery of this unit is at the very top of the section in one of the last bedding planes. There are extensive amounts of a twisty worm-tube called Filograna (or at least something close to it). You can see it in the above image. I was told earlier it was a “mat”, but it appears to be instead broken fragments of tube accumulations scattered about. Strange critter, this worm.Echinoid tests 040814The marls of the Zichor have an impressive echinoderm content. Since they have calcitic tests, they are very well preserved. Above are five heart urchins showing their classic pentameral symmetry.

Echinoid test plates 040814Here are fragments of a cidaroid echinoid test. In the middle of each plate is a circle with a boss extending outwards. Spines were attached to these, one of which is included in the image. I hope on our later expedition we can find whole specimens. Students are always up for these discovery challenges.

Asteroid ray oral 040814This was a first find for me: an asteroid (sea star) ray fragment. I don’t think I’ve ever found a sea star fossil before. We are looking above at the oral side where tube feet would have extended.

Asteroid ray aboral 040814This is the other side of the fragment — the aboral side. Beyond being cool, I’m afraid there is not a lot of significance for this fossil unless I can identify it further. Sea stars are famous for living in all sorts of marine environments, from the intertidal to deep trenches.

Some future Wooster students are going to have a good time with this unit sorting out the paleontological, sedimentological and stratigraphic contexts and then comparing this tropical fauna to the better known assemblages in the temperate north.

A Triassic afternoon in southern Israel

April 8th, 2014

Mitzpe Ramon distant view 040814MITZPE RAMON, ISRAEL–This afternoon I walked through the spectacular Middle Triassic sections in Wadi Gevanim on the southern side of the Makhtesh Ramon structure. I will be on a fantastic trip this Thursday to a little-visited Triassic section farther south, so I wanted to refresh my memory of these units. The above image is looking north from Wadi Gevanim to Mitzpe Ramon just visible on the cliff edge of the makhtesh. (What a setting, eh?)

Nautiloids Ammonites 040814I found myself almost completely repeating an entry from last year on Wadi Gevanim (which had the added bonus of students in it). Today I gathered some impressive fossil cephalopods from the Saharonim Formation (Middle Triassic, Anisian-Ladinian) for a group photograph. I note only now that one of the nautiloids above appears last year as well! From the upper left going clockwise: nautiloid, ammonite, nautiloid, ammonite. All are internal molds (the outer shell has been removed).

Nautiloid 040814That upper left nautiloid is worth a closer look. The mold has been split down the middle showing the septa (internal walls dividing the chambers) and an impressive “beaded” siphuncle (connecting tube) running the length of the conch (shell).

Terebratulids 040814Finally, here is a handful of the common terebratulid brachiopods from the Saharonim. Speaking of which, have I mentioned the species Menathyris wilsoni from the Saharonim? You certainly must meet Menathyris wilsoni!

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!

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