Archive for May, 2011

A gecko’s end

May 31st, 2011

MITZPE RAMON, ISRAEL–What is Will examining so intently? There was drama on the outcrop this afternoon. We are used to seeing cute little geckos clinging to the rocks we study. As we skirted the edge of a limestone cliff, Will saw a very long and narrow snake dash after a lizard. We all watched as the lizard dived down the rocks of the cliff, scrambling to the bottom. The snake followed its every move, catching it in a talus pile. The circle of life.

You can see the snake’s coils here and a motionless lizard. Why is he holding so still in such a dangerous place?

Because on closer view we see that the snake has him by the head and has started to slowly swallow him.

This encounter reminds me of the lizard-scorpion battle witnessed by the 2010 Wooster Geologists team in Utah.

This was our last field day in Israel. Tomorrow morning, very early (4:00 a.m.!), we start the long drive north to Tel Aviv and Ben Gurion airport. Then the long flight to Newark and then Cleveland. It has been another wonderful adventure of geology, biology and history.

Wooster Geologists at the Siege of Lachish (2700 years later)

May 30th, 2011

MITZPE RAMON, ISRAEL–Every time I visit the British Museum in London, I examine the fascinating relief from Nineveh showing The Siege of Lachish. The detail is extraordinary as the story is told in sequence through dozens of panels. It is a brutal tale of conquest and pillage, giving insights into the heart of an empire long since extinct. Today Will and I visited the archaeological site of Lachish on the way back from Jerusalem. Our friend Yoav gave us an excellent tour — and we were the only people there. The main gate and approach road is shown in the image above.

Lachish was a walled city at the boundary between the hill country and the coastal plain. It is mentioned several times in the Bible, most notably when captured by Joshua from the Canaanites (see Joshua 10: 1-32). The famous Siege of Lachish was in 701 BCE when the Assyrian king Sennacherib sought to conquer the tiny nation of Judea (see II Kings 18). Lachish watched over the coastal plain and the main approaches to Jerusalem.

The city wall on the approach to the main gate. Soldiers marching up the road would have their right sides exposed to this wall. Since they typically carried their shields on their left arms, they are here vulnerable to defending archers at the top of the wall.

The Assyrians did not attack Lachish directly by the main gate. They instead built a siege ramp of stones and wood on the weakest corner of the walled city. They wheeled battering rams and towers up this ramp, eventually breaching the wall despite a counter-ramp attempted by the Judean defenders. This is one of the best preserved siege ramps in the ancient Near East.

A view of the inside of the city showing remnants of the commander’s palace at the highest point.

The view from Lachish into the Judean Hills. Hebron is visible at the top of the distant ridge.

An archaeological controversy (or at least it should be one) is this well in or near the city walls of Lachish. Geologists have shown conclusively that it was a failed well — it did not reach the aquifer (Weinberger et al., 2008). The builders of the well may have thought that all they had to do was penetrate down as far as the wells outside the city to hit water, but those wells were in a perched aquifer of alluvium. The Lachish well is in Eocene chalk. The city may have been running out of water when it was besieged.

It was a privilege to visit such an historic site and have the luxury of a personal guided tour by Yoav.

Reference:

Weinberger, R., Sneh, A. and Shalev, E. 2008. Hydrogeological insights in antiquity as indicated by Canaanite and Israelite water systems. Journal of Archaeological Science 35: 035-3042.

 

Wooster Geologists at the Center of the World

May 30th, 2011

Our visit to Jerusalem was to meet geologists at the Geological Survey of Israel main complex in the western part of the city. Those discussions went very well and we met new people and learned much. Will and I also took the opportunity to spend a few hours in the Old City. Here are some of the sites. The view above is of the Old City from Mount Scopus.

When we say that Jerusalem is the “Center of the World“, we are following a medieval tradition illustrated by this European manuscript page reproduced as a tiled image at the City Hall.

The Geological Survey of Israel headquarters have a very unassuming (and secure) entrance. This is an old World War II British military base that was on the outskirts of the city but is now surrounded by an Ultra-Orthodox Jewish community. It is a wise move not to advertise the very secular activities going on in there!

Our main walking route from the Survey to the Old City was Jaffa Street, which leads directly to Jaffa Gate. This is looking northwest. There is a new tram system being tested, thus the tracks in the road and lack of cars.

Will in the Old City market on our way to the Church of the Holy Sepulchre.

Outer courtyard of the Church of the Holy Sepulchre. All those people going in and out of that one doorway. Jerusalem now receives a record three million visitors a year.

Turns out the Center of the World is actually within the Church of the Holy Sepulchre … and its exact spot has been marked!

There are very few places in the Church of the Holy Sepulchre where you can see the original bedrock of the area. This is a famous crack in the rock below what is supposed to be the crucifixion site and above what is known as Adam’s Grave. Note the strain gauge across the joint. There are geological concerns about the stability of the bedrock and monumental structures built on top of it. I can’t imagine how the Israeli authorities got religious sanction to install that instrument!

Crepuscular rays descending from the dome of the Church of the Holy Sepulchre. The top of the Holy Sepulchre structure is at the bottom of the image.

Finally, we visited the Western Wall revered in Judaism. Above it (and not visible in this image) are the Islamic holy sites in Jerusalem: the Al Aqsa Mosque and the Dome of the Rock. We thus visited in the space of a few hours sacred spaces of the three Abrahamic religions. Center of the World indeed.

 

Wooster Geologists return to the Dead Sea

May 30th, 2011

MITZPE RAMON, ISRAEL–Today Will and I went to Jerusalem for meetings at the Geological Survey of Israel headquarters. Much more on that later. On the way Yoav drove us along the west coast of the Dead Sea. Will got a chance to dip his hand in the warm and heavy water, and we talked about salt, shorelines and sinkholes.

These are halite (salt) deposits on the Dead Sea shore near Will’s feet above. Halite encrusts all that this water touches, from rocks and sediment to abandoned tires.

This slope above the highway on the west shore of the Dead Sea shows ancient shorelines from roughly 26,000 to 14,000 years ago. The sea then was salty but only about half the current salinity. Shorelines fluctuated but generally fell during this 12,000 year interval.

A serious environmental problem along the western shore is the development of huge sinkholes. These are forming because the Dead Sea is losing water rapidly (it drops about a meter per year) and freshwater is now finding thick salt deposits underground. The water dissolves the salts, forming caverns that eventually collapse and make the pits above. Often the pits then fill with water, making small ponds that have their own flora and fauna.

Mishash, b’gosh

May 29th, 2011

MITZPE RAMON, ISRAEL–Today Will and I drove south, east and north to meet Dr. Yael Edelmen-Furstenburg of the Geological Survey of Israel. She gave us a most excellent tour of the Mishash (pronounced ME-shawsh) Formation (Campanian, Upper Cretaceous) in the Wadi Ashosh region (shown above) near Zuqim and Tsofar in the Negev Desert. We talked much about the fossil fauna, particularly the trace fossils in soft and hard substrates. There could be many future Wooster Independent Study projects in this formation, especially here where it is so diverse.

As seen above, much of the Mishash Formation consists of bands of chert. The folds are syndepositional (formed at the time of deposition) as part of the Syrian Arc deformation. This makes for some very interesting local stratigraphy and depositonal patterns.

The Mishash Formation has exquisite fossil shell beds, often silicified (replaced with silica). Above you can see gastropods and bivalves.

An old Cretaceous friend, the ammonite Baculites, is used to sort out the biostratigraphy of the Mishash. They are identified by the style of ribs they have on the outside of the conch.

Like everywhere else in the Negev Desert, shade is a bonus. We always appreciate the acacia trees, even if their shade is not so complete. Will is standing here next to the Geological Survey of Israel vehicle. Shlomo, an old friend and the driver, gave us quite the off-road adventure. Many people pay for such tours!

Incidents of Travel in Southern Israel

May 29th, 2011

Flat tire at N30.54352°, E35.14007°.

Near miss (if we had been eating lunch here, say, 15 years ago).

Wooster’s Fossil of the Week: Mysterious tentaculitids (Devonian of Maryland)

May 29th, 2011

The sharp little conical fossils above are common Paleozoic fossils, especially in the Devonian. They are tentaculitids now most commonly placed in the Class Tentaculitoidea Ljashenko 1957. Tentaculitids appeared in the Ordovician and disappeared sometime around the end of the Carboniferous and beginning of the Permian. These specimens are from the Devonian of Maryland.

The systematic placement of the tentaculitids has been controversial. Their straight, narrow shells are usually ornamented by concentric rings, and many had septa (thin shelly partitions) inside the cones. The microstructure of the shells is most interesting — it looks very much like that of brachiopods and bryozoans. For this reason and several others, several of my colleagues and I believe the tentaculitids were lophophorates (animals that filter-feed with a tentacular device called a lophophore). They may thus be related to other problematic tubeworms like microconchids and cornulitids (Taylor et al., 2010).

Tentaculitids from the New Creek Limestone (Lochkovian, Early Devonian) of New Creek, West Virginia.

Knowing how the tentaculitids fit into an evolutionary scheme, though, has not helped us figure out what they did for a living. The figure below, from Cornell et al. (2003), shows these funny cones in just about every lifestyle imaginable!

References:

Cornell, S.R., Brett, C.E. and Sumrall, C.D. 2003. Paleoecology and taphonomy of an edrioasteroid-dominated hardground association from tentaculitid limestones in the Early Devonian of New York: A Paleozoic rocky peritidal community. Palaios 18: 212-224.

Taylor, P.D., Vinn, O. and Wilson, M.A. 2010. Evolution of biomineralization in ‘lophophorates’. Special Papers in Palaeontology 84: 317-333.

A wall of Cretaceous ammonites

May 28th, 2011

MITZPE RAMON, ISRAEL–On our way back from Eilat this afternoon, Will and I took a short hike to see the “Ammonite Wall” on the southern outside beds of Makhtesh Ramon. It is an impressive tilted array of large ammonites in the Tamar Formation (Cenomanian). Current thoughts are that this represents a massive death assemblage. The ammonite conchs, which all seem to be of the same species, washed into an embayment and were buried. This is not uncommon as ammonite conchs probably filled with gases after death and floated great distances. They are all preserved as internal molds, with a few, such as the one below, showing their suture patterns.

A visit to a dying reef system

May 28th, 2011

Fringing coral reef seen from the top of the Underwater Marine Observatory tower near Eilat, Israel.

EILAT, ISRAEL–When I first visited the Underwater Observatory Marine Park outside Eilat on the Red Sea coast near the Egyptian border, I was enchanted. An elegant steel and glass tower was built into a reef so that you can descend well below sea level and look out at a living, natural reef. I’ve brought students to this Observatory ever since to enjoy the beauty of a reef close-up without having to get wet. It is also a splendid place to see living analogues of the many organisms we are studying as fossils in the Jurassic and Cretaceous.

Closer view of the reef in the first image. Almost all the corals are dead.

Alas, the Eilat coral reefs are dying quickly. I see a significant difference in the health of the reefs in the last eight years. Most of the framework corals are completely dead, leaving gray aragonite skeletons to be sparsely inhabited by sponges, feather worms and the inevitable algae. The park tries gamely to keep up appearances at the observatory windows, but it is clear that the dwindling diversity of fish is now the primary attraction, not the corals themselves.

Will Cary looking out one of the underwater windows into the coral reef.

Coral reefs are dying all over the world, but their rate of disappearance in the Red Sea is unusually high. There are many causes, my biologist friends tell me, most related to the narrow nature of the Gulf of Eilat here. Many ships pass through daily, water-loving tourists are abundant, and wastes inevitably drain from the cities of Eilat and Aqaba into the sea. There is also a problem of sand being added to hotel beaches which gets redistributed onto living reef.

The coral reefs viewed from below. The framework is mostly dead coral skeleton.

Fifty years ago there were about 10 square kilometers of living coral reef in this area. Now it is less than 2.5 square kilometers, and much of this remaining reef is so stressed that no new corals are recruited. Very sad.

In the future I may be showing my students a few living corals preserved in the aquaria of the Underwater Observatory Marine Park, and then looking out at what happens to an ecosystem when the reefs die.

A rare late May rain in the Negev

May 28th, 2011

MITZPE RAMON, ISRAEL–The only other time I’ve seen rain in southern Israel was with Elyssa Krivicich on our March 2008 trip. By May the rains are done in this part of the world. Nevertheless, it rained last night and then sprinkled on us as we drove south to Eilat this morning. The temperature has also dropped a good 6°C, which suits us just fine.

This is the 400th post on the Wooster Geologists blog! It is also near our two-year anniversary. It appears from our statistics (which I do not fully understand) that we have had 21,793 visitors and 163,072 pageviews. I’m not sure if those are unique visitors or what a “pageview” is, but I know we’ve had enough feedback to make this project much fun.

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