Wooster Geologists in Jerusalem

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.

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Return to the Ora Formation

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.

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Adventures in the Triassic: Exploring the Gevanim Valley in Makhtesh Ramon, southern Israel

2_NordmarkiteStock070913MITZPE RAMON, ISRAEL–The second visit of the day for Wooster’s Team Israel 2013 was to the Gevanim Valley on the south side of the Makhtesh Ramon structure. This is a fascinating place where Cretaceous intrusions formed an uplifted dome exposing Triassic sedimentary rocks. It is a rare place to see abundant Triassic marine fossils. Our first stop was a nordmarkite stock intruded into the Gevanim Formation (Middle Triassic, Anisian). We always dedicate this image to our own Dr. Meagen Pollock who knows what nordmarkite is without having to google it.

3_GevanimRamonalinidSite070913Our first task was to locate the Gevanim Formation and examine the many specimens of the large bivalve Ramonalina ramanensis to look for rare Triassic encrusters. Above is an outcrop of the part of the Gevanim which has large numbers of this dark-colored, shoe-shaped clam.

4_Ramonalina070913Here are two nearly complete specimens of Ramonalina ramanensis. Alas, we found not a single encruster. The rumor that there are microconchids on these shells seems to be false. Science marches on.

5_LizzieSaharonim070913Above the Gevanim Formation is the Saharonim Formation (Middle Triassic, Anisian-Ladinian). Lizzie Reinthal is here standing near the base of it exposed in the western part of the Gevanim Valley. This is a very fossiliferous limestone and marl that is extremely well exposed here.

6_CephalopodsSaharonim070913Nautiloids and ammonoids are very abundant in the Saharonim. In fact, just about every large object in this exposure of the unit is one or the other. The coin in the image above is sitting on an ammonoid (a ceratite). The other fossils are internal molds of nautiloids.

7_SaharonimBrachiopods070913Our goal today, though, was to find terebratulid bachiopods with original calcite still preserved. We found dozens, a few of which are shown above. These are mostly of the genus Coenothyris. These specimens are destined for isotopic analysis in the laboratory of Dr. Pedro Marenco at Bryn Mawr College. Mission accomplished.

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“The Carpentry” in Makhtesh Ramon: Unexpected columnar jointing

1_JointedSandstone070913MITZPE RAMON, ISRAEL–At first glance this rocky outcrop in the middle of Makhtesh Ramon appears to be a typical columnar-jointed basalt. We’ve seen this many times on our blog (for example here and here). However, these rocks are entirely a quartzose sandstone. They have the typical polygonal joints of a cooled lava flow, but the rock is an unmetamorphosed sedimentary unit. This remarkable site is known as “the carpentry” (Haminsara) in the park.

How did these joints form? It is not from the sandstone melting and then cooling, like you’ll see in some places on Wikipedia. (And some people think this is basalt, which is a good reason for more interpretive signs in this place.) Likely it was a hydrothermal process by which superheated water from nearby intrusions warmed up the sandstone until it expanded a bit, and then it cracked along these joints during cooling. The sandstone was never heated to temperatures that would turn it into quartzite, much less liquid. Columnar-jointed sandstone is rare but not unique, as you can see here and here.

This was the first stop for the Wooster Geologists in Israel today as we explored parts of Makhtesh Ramon to follow up on various small projects.

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

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!

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A day of geological exploration in the Negev: Matred Formation fossils and bonus petroglyphs

8_OscarSilicifiedRingMatred070813MITZPE RAMON, ISRAEL–Our third stop in our geological journey today was 19 km north of Mitzpe Ramon (N 30.76084°, E 34.72020°) at another outcrop of the Matred Formation (Middle Eocene). We again had silicification, but no corals this time, The silica replaced the original limestone in a very strange way, producing these dark rings. Since silica is harder than limestone, the surrounding unreplaced limestone erodes faster, leaving the silicified rings in relief. They look anthropogenic, but they’re entirely natural. Again, mysteries abound.

9_SilicifiedBivalvesMatred070813In this close view of the silicified limestone are numerous bivalve shells that were replaced with silica just like the matrix. They appear to be a random distribution of shells with no preferred orientation.

10_SilicifiedFossil070813There are two fossils here replaced with silica. We’ll let the readers guess what they are.

11_Petroglyph070813These curious rings of black rock on the top of a hill attracted local peoples. Over the centuries (no one knows exactly how many or when) they carved numerous petroglyphs through the patina on the rock surfaces. We will also entertain guesses as to what is represented here!

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A day of geological exploration in the Negev: Silicified corals in the Matred Formation (Eocene)

MatredFormationView070813MITZPE RAMON, ISRAEL–Our next stop on this day of exploration was 32 km southeast of Mitzpe Ramon at outcrops of the Matred Formation (Middle Eocene). The location is N 30.36899°, E 34.98655°. Look at those coordinates on Google Maps and you’ll see that they are from the peak of that black mountain on the right of the above view. The black color is from the weathering of thoroughly-silicified (infused with silica) coral-rich limestones. Ordinarily paleontologists tend to stay away from such preservation because the matrix as well as the fossils are coarse, hard chert. These fossils, though, are important because they give strong clues about the depositional environment of the sediments. In this case, in situ coral reefs mean shallow water.

MatredCoral070813This is what the silicified corals look like in this part of the Matred Formation. We are looking down on the top of a colony. The holes represent the original corallites. Material like this cannot be identified to more than the family or genus, but we see enough to know that they are corals.

NummulitesMatred070813In this piece the bean-shaped fossils are large benthic foraminiferans that still retain their original calcareous skeletons. The matrix around them has been silicified. This type of preservation remains a mystery, especially when in the same unit we see the same fossils have been silicified and the matrix is not. More geological puzzles!

WadiView070813This wadi near the site is so beautiful I wanted to include an image. This would be a fun place to work, although maybe the spring would be more hospitable!

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A day of geological exploration in the Negev: the Hazeva Formation (Lower Miocene)

1_NachalParanFault070813MITZPE RAMON, ISRAEL–It is a tradition with the Wooster Israel expeditions to spend one day with our colleague Yoav Avni geologically explore areas beyond those associated with our present research topics. This is the way we plant seeds for future research endeavors — and Senior Independent Study projects. Today we went to four sites, which I will present in brief vignettes.

Our first stop of the day was in Nachal Paran at N 30.32329°, E 34.96388° about 35 km southeast of Mitzpe Ramon. The image of above is from our outcrop looking up at the faulted boundary of a large graben in which the valley is formed. Preserved within this down-dropped structure is a thick section of the Lower Miocene Hazeva Formation.

2_HazevaFormation070813Most of the Hazeva consists of reddish sandstones and conglomerates deposited by a very large river system that was flowing from the Arabian Peninsula into the Mediterranean. There have been a variety of African-derived mammal fossils in this unit, including elephants and giraffes. The unit of interest for us today is the gray rock at the base of the above image. It is a thin limestone unit no more than one meter thick. Its top has a scalloped pattern that may be due to ancient karstic weathering when the river deposited muds and gravels upon it. It appears to be a lake deposit formed just before the river moved into the region.

3_HazevaCloser070813Team Israel 2013 is here looking at a cross-section of the lacustrine (lake-formed) limestone and the sediments beneath it. One of the issues is how do we know that the limestone was formed in a lake. The best clue is the occurrence of tiny high-spired gastropods throughout the matrix. Another would be the presence of trace fossils that may represent the horizontal trails of snails and/or freshwater arthropods like isopods or insects. There is a pervasive pattern of vertical tubes that remains mysterious. Are they trace fossils or some sort of diagenetic phenomenon? A further question is why this lake was there in the first place considering that it sits in a section almost entirely formed of typical terrestrial siliciclastic sediments. Does it represent a brief climate change? A tectonically-induced change in the local hydrogeology? Plenty of questions here for future geological researchers.

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Goodbye, Makhtesh Gadol (for now)

GoodbyeMakhteshGadol070713MITZPE RAMON, ISRAEL–Today Team Israel 2013 had its last visit to Makhtesh Gadol, marking the end of Lizzie Reinthal’s and Steph Bosch’s fieldwork. We collected our last specimens from the Matmor Formation, which is exposed only in the center of this magnificent structure. The students above are looking down into the northern part of the makhtesh from the viewpoint at Mount Avnon.

MakhteshGadol070713This is a view from the same spot looking south along the western wall of the makhtesh. You can see a bit of the curvy, narrow road below that we used to enter and exit the makhtesh. This road was built by the British during World War II when they thought there might be oil underneath this breached anticline.

MG_BronzeAgeStructure070713This ring of stones is the remnant of a Bronze Age livestock pen, along with a probable small shelter for the shepherd in the lower left. This features are found throughout Makhtesh Gadol, usually up on the flanks of the walls or the Matmor Hills. I happened to come across this one in today’s walkabout.

LastCollecting070713Finally, here are students collecting at our last site — the southernmost exposure of the echinoderm-rich subunit we’ve found to be so productive. This morning we found … wait for it … two more bryozoans! This is usually not big news in most of the places I’ve worked, but it sure is here. They are again runner-types, but not Stomatopora. Much more to report on these after we get back home with them.

We still have five more working days in Israel. One will be devoted to finishing Oscar’s fieldwork, one to finishing smaller projects in the Makhtesh Ramon area, one to exploration of geological sites Yoav has chosen for us, one for a trip to Jerusalem and the headquarters of the Geological Survey of Israel, and a final day to make sure we’ve done all we came to do.

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Wooster’s Fossil of the Week: An echinoid from the Eocene of France

585 Echinolampas ovalis M Eocene Civrac-en-Médoc FranceThe above is a specimen of the echinoid Echinolampas ovalis (Bory de St Vincent, 1824) from the Eocene of Civrac-en-Médoc, France. We are looking at what is called the aboral surface — that part of the organism on the other side of its mouth. (I’m sure by now you recognize the little barnacle boring near the bottom of the skeleton.) Below is the oral view of the same specimen.585 Echinolampas ovalis M Eocene Civrac-en-Médoc France oral

Echinoids are a kind of echinoderm with a very long evolutionary history from the Ordovician to today. They include sea urchins, heart urchins and sad dollars, along with a few others. All echinoids are covered in life with numerous spines. These spines almost always fall off after the death of the organism, leaving the smooth test we see here. The tiny circles covering the surfaces of this specimen are spine attachments. In life this would have looked like a spiky ball.

In the center of the oral view is a large hole where the mouth was. The plates surrounding this are called the peristome (around-mouth). At the bottom on the oral view are two holes. The larger is where the anus was located (within the periproct of plates); the smaller is a circular boring, likely from a gastropod predator. Since the periproct is not in the center of the aboral surface, this is what is known as an irregular echinoid.
Echinolampas_ovalis_Eocene_Civrac-en-Médoc_France_CloseUp052013Above is a close-up of the center of the aboral surface. The radiating rows of holes were where tubefeet extended. These soft structures at the end of the water vascular system were used for locomotion, moving bits of food towards the mouth, and even respiration. The very center is a finely-porous plate called the madreporite (the opening for the water vascular system). The four holes around it are genital pores for releasing gametes into the water during reproduction. For a simple, globular organism, the echinoid is amazingly complex.
450px-Bory_Saint-Vincent_1778-1846Echinolampas ovalis was named by a scientist with a complex life story of his own. The dashing Jean Baptiste Bory de Saint-Vincent (1778-1846) was one of a remarkable generation of French zoologists. He began his career as a naturalist, studying the fauna on various French possessions in the Indian Ocean. He returned to France and became a soldier in the Napoleonic Wars, serving in the battles of Ulm (1805) and Austerlitz (1805), and participating in the disastrous French campaign in Spain. He was a Bonapartist to the end, opposing the Bourbon restoration, which resulted in exile from France. After his politics faded, he returned to France in 1820 and resumed his career as a traveling naturalist. He named dozens of living and fossil species of invertebrates after the wars, including our quiet little echinoid in 1824.

References:

Kier, P.M. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections 144(3), 262 pp.

Roman, J. 1965. Morphologie et evolution des Echinolampas (Echinides, Cassiduloides). Memoires du Museum National d’Histoire Naturelle, Nouvelle Serie, C, 15, 1-341.

Thum, A.B. and Allen, J.C. 1976. Reproductive ecology of the lamp urchin Echinolampas crassa (Bell), 1880 from a subtidal biogenous ripple train. Transactions of the Royal Society of South Africa 42: 23-33.

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