Archive for September, 2009

Watched

September 8th, 2009

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MAKHTESH GADOL, ISRAEL–Our primary field area on this trip is near Dimona, Israel.  Outside the town is a famous facility with domed buildings and a very well guarded fence, complete with cameras and razor wire.  My Israeli friends tell me that it is a top secret ice cream research complex.

Part of the security for the production of all this “ice cream” is a tethered blimp which rises high above the desert, presumably carrying loads of cameras and other remote sensing devices.  Today we saw it being slowly reeled out, first rising as a startling image on the horizon of the makhtesh, and then almost disappearing in the distant sky.  We waved hello.

“I Know a Tree …”

September 8th, 2009

MAKHTESH GADOL, ISRAEL–Shade of any kind is rare in the Negev Desert, especially from trees.  At lunchtime in the field we want very much to be out of the sun, so usually someone suggests a lonely tree they know along a road or up some path.  The favorite tree for many Wooster geologists working in Makhtesh Gadol is the acacia pictured below.  Sure we’ve had to endure the camel flies and other camel offerings, but that shade has been heavenly.

One of the very few trees in Makhtesh Gadol.  This is an acacia.

One of the very few trees in Makhtesh Gadol. This is an acacia.

The acacias in the Negev are critical to animal ecosystems as well as in human ecology.  They are of a species which originated in Africa and migrated north into the Middle East.  They are genetically programmed to produce greenery and flowers during the African  monsoons in the summer.  As a consequence they are the only green and productive plants in the dry Negev summers, sustaining many animals with their leaves, flowers and beans.  The Bedouin Arabs depend on the acacia to feed their livestock during the hot and dry months in Israel and the surrounding countries.  Geologists are grateful for the high spreading branches which make a natural desert umbrella.

Leaves and flowers of the acacia tree shown above (left); beans and their pods on the ground beneath the tree.

Leaves and flowers of the acacia tree shown above (left); beans and their pods on the ground beneath the tree.

Bronze Age Predecessors

September 7th, 2009

MAKHTESH GADOL, ISRAEL–My field area contains several rocky ruins like the structure pictured below.  These are the remains of shelters and livestock enclosures constructed during the Bronze Age about 4000 years ago.  Flint chips and the occasional scraper can be found in and around these sites.  Sometimes they are so common that I have to pick them out of my fossil collections.  It is a nice touch to this fieldwork to have evidence of human antiquity in the same places I’m studying the very deep past.

Bronze Age structural remains in Makhtesh Gadol.

Bronze Age structural remains in Makhtesh Gadol.

Wandering in the Wilderness (Literally)

September 7th, 2009

MAKHTESH GADOL, ISRAEL–Today I mapped exposures of a particular fossiliferous unit in the Matmor Formation. It meant climbing up and down steep hills bent over the ground scanning for fossils. It is a remarkable skill we humans have for visually sorting through millions of images and then suddenly noting the one set of curves or angles or colors that identify a target. In my case I walked over thousands of square meters of rocky ground to spot bits of fossil crinoids, as in the photos below.

Crinoid calyx as found in the Matmor Formation (left); calyx fragments (right).  I use the two-shekel coin for scale because conveniently it is two centimeters in diameter!  Specimens found at N30.92907°, E34.97295°.

Crinoid calyx as found in the Matmor Formation (left); calyx fragments (right). I use the two-shekel coin for scale because conveniently it is two centimeters in diameter! Specimens found at N30.92907°, E34.97295°.

These crinoids are indicators of a unique community of echinoderms, brachiopods, sponges and corals found near the middle of the Matmor Formation. I collected enough specimens from several localities for analysis in the Wooster paleontology lab this winter and spring. I hope these fossils can be the basis of a student Independent Study project in Israel next year. It was much fun collecting these specimens because I never knew what treasure would turn up on the next hillside. A bit dangerous this kind of enthusiastic collecting in the desert because it is easy to forget to drink water — or even to stand up straight occasionally!

The sorted contents of one of my collection bags.  The items in the left two-thirds are crinoid parts.  Hotels probably don't like the way I use their towels in the afternoon!

The sorted contents of one of my collection bags. The items in the left two-thirds are crinoid parts. Hotels probably don't like the way I use their towels in the afternoon.

Ammonite Identified

September 6th, 2009

JERUSALEM, ISRAEL–I don’t really think the readers of this blog have been anxiously waiting to hear the taxonomic identification of the ammonite I found in the Matmor Formation last week.  It is worth a note, though, to briefly describe how I now know the beauty is Peltoceras solidum.  Yoav and I traveled today to Jerusalem to work in the offices of the Geological Survey of Israel.  While there I was able to examine the ammonite collections of Ze’ev Lewy, a retired paleontologist with the Survey.  He collected the specimen pictured below from the Matmor several years ago.  Dead ringer for my paltry fragments, which show the same external ornamentation and the same internal suture pattern.  Case solved!

Ammonite found in the Matmor Formation at Makhtesh Gadol by Ze'ev Lewy of the Geological Survey of Israel.

Ammonite found in the Matmor Formation at Makhtesh Gadol by Ze'ev Lewy of the Geological Survey of Israel. The close-up on the right is of the suture pattern highlighted with a pencil.

A Visit to The Galilee

September 5th, 2009

ROSH PINA, ISRAEL–This weekend my friends the Avni family took me on an overnight trip into the Galilee. It was spectacular and highly informative — they called it the “Mark Continues to Discover Israel” tour. The ostensible purpose was to attend a reunion of Noa Avni’s kibbutz school class, but we also took in numerous cultural, historical and geological (of course!) sites.

We drove from Mizpe Ramon on Friday afternoon north up the Rift Valley, following the west coast of the Dead Sea and then the west bank of the Jordan River to Tiberias on the Kinneret Lake (Sea of Galilee). We then continued north in the Galilee to a little town a few kilometers from Rosh Pina. We then had a barbecue dinner and conversations into the late evening before sleeping on mattresses in a grassy square. I asked many, many questions of my new Israeli friends (my Mother would be so proud) and learned much.

Looking into the Galilean hills from Rosh Pina along the very old road to Safed.  Note the ancient olive trees and the gray rocks of the distant hills, which are Eocene limestones.

Looking into the Galilean hills from Rosh Pina along the very old road to Safed. Note the ancient olive trees and the gray rocks of the distant hills, which are Eocene limestones.

The next day we walked around the old part of the beautiful hillside city of
Rosh Pina (just down the mountain from Safed), talked to a man who runs environmental education programs, and had a long lunch with Yoav’s sister’s family in their hilltop home near Karmiel. We drove back down the Rift Valley to return to Mitzpe Ramon late this evening.

Rosh Pina from the Nimrod Viewpoint.

Rosh Pina from the Nimrod Viewpoint.

I was most impressed by the friendliness and candor of the people I met (I know — it is no surprise that Israelis are candid!), the lingering damage from the 2006 Hizbollah rocketing of northern Israel (mostly burned forests now and gaps in streets where there were once houses), the complex carbonate rocks which make up most of the hills in Galilee (my rocks in the Negev are much simpler), and the full moon tonight which rose bright red as its light passed through Saharan dust low on the horizon.

The delightful backyard of an environmental educator in Rosh Pina, Israel.

The delightful backyard of an environmental educator in Rosh Pina, Israel.

A Most Unusual Clam from the Triassic of Israel

September 5th, 2009

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MAKHTESH RAMON, ISRAEL–The Triassic was a time of unusual evolutionary innovations.  The Permian extinctions immediately before the Triassic may have wiped out up to 95% of marine animal species, so the survivors had considerable “empty niche space” to fill as they adapted to new environmental conditions with far fewer competitors.  The strange clam above is now part of this history.  On the left you see a view from above and front of the clam in living position.  It has a flattened base which it used to sit on the seafloor with its two valves extended up into the seawater to filter-feed.  On the right is a view of the base of this clam showing the junction between the two valves.  Note that the valves are not symmetrical as they are in most clams.  This clam was an “edgewise recliner”, meaning it sat on its edge (which it flattened over evolutionary time).  There is no other clam like it in the fossil or living record, and it is found only in one rock unit in the Negev Desert.

Allison Mione (’05) studied this clam and its living environment as part of her Independent Study project, and Tom Yancey (Texas A&M University) and I continued to work on it after she graduated.  The three of us now have a paper in the journal Palaeontology coming out later this year interpreting this clam as a new genus representing a new family of bivalves.  I took the opportunity yesterday to find a few more examples of this unique creature for museum collections.

This fossil was not thoroughly described in the past because finding whole specimens is very difficult.  We found one spot where the clam-bearing rock unit (the flat, tilted bed in the middle ground of the photo below) was dragged along a fault and bent in such a way that large blocks of the rock collapsed downhill upon exposure, releasing whole fossils.  As far as I can tell, this is the only place the whole fossils can be collected (N30.58759°, E34.88685°).

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A Jurassic Ammonite Up Close

September 3rd, 2009

MITZPE RAMON, ISRAEL–I can’t help but show off the ammonite I found today in the middle of the Matmor Formation (Goldberg Subunit 51) at Makhtesh Gadol.  These photos are the best I could do on a kitchen sink with overhead lighting.  (Clearly I have time on my hands once I get back to my room in this little town!)

This is the largest fragment of the ammonite.  It is not a lot to look at, I admit, but it is an important indicator of the time the sediments were deposited and the chemistry of the seawater when the animal lived and died.  It is an internal mold, meaning that it is the sediment inside the shell after the shell dissolved.  What is significant here is that this mold is encrusted by oysters (one is indicated), serpulid worms, and foraminiferans, showing that the shell dissolved and the sediment cemented early on the seafloor -- an example of "Calcite Sea" geochemistry.

This is the largest fragment of the ammonite. It is not a lot to look at, I admit, but it is an important indicator of the time the sediments were deposited and the chemistry of the seawater when the animal lived and died. It is an internal mold, meaning that it is the sediment inside the shell after the shell dissolved. What is significant here is that this mold is encrusted by oysters (one is indicated), serpulid worms, and foraminiferans, showing that the shell dissolved and the sediment cemented early on the seafloor -- an example of "Calcite Sea" geochemistry.

On the left is a closer view of the outside of the ammonite internal mold.  Note the pattern of oval-shapped divots.  I have no idea what they are, but they represent some sort of objects that were in the shell before it dissolved away.  On the right is a close-up of the complex ammonitic suture, which was the boundary between the internal septal walls and the outer shell.

On the left is a closer view of the outside of the ammonite internal mold. Note the pattern of oval-shapped divots. I have no idea what they are, but they represent some sort of objects that were in the shell before it dissolved away. On the right is a close-up of the complex ammonitic suture, which was the boundary between the internal septal walls and the outer shell.

That’s probably enough paleontology for the day.  If anyone wants to identify this ammonite before I get home, I’ll be grateful!

Tools of My Trade (At Least for Today)

September 3rd, 2009

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MAKHTESH GADOL, ISRAEL–The fieldwork could not have been better, although if you watched me all day in the desert sunlight you would have thought otherwise. After I hiked up into the Matmor Hills to find the right horizon, I spent hours in the same place collecting fossils off the surface and sieving the sediments to obtain tiny shells (especially of thecideide brachiopods). The goal is to thoroughly understand the paleontology of this unit, including how these organisms interacted with each other in that ancient Jurassic sea. The persistence paid off with a diverse set of brachiopods, corals, sponges, echinoids, serpulid worms, bivalves, gastropods, and the first ammonite I’ve seen in the Matmor Formation. There is enough complexity in this one site to support at least another two Senior Independent Study projects.

This view of a coral in cross-section shows how complex bioerosion can be.  You can see several holes in the brown coral matrix filled with white sediment.  Inside these borings are cross-sections of bivalve shells.  Note that some borings have more than one set, meaning the hole was occupied by nestling clams after the borer died.  The patches of shiny grey are silicified regions of the coral skeleton.  Since the coral was aragonitic, its original skeleton has been replaced by several minerals.

This view of a coral in cross-section shows how complex bioerosion can be. You can see several holes in the brown coral matrix filled with light tan sediment. Inside these borings are cross-sections of bivalve shells. Note that some borings have more than one set, meaning the hole was occupied by nestling clams after the borer died. The patches of shiny grey are silicified regions of the coral skeleton. Since the coral was aragonitic, its original skeleton has been replaced by several minerals.

Returning to the Big Makhtesh

September 2nd, 2009

MAKHTESH GADOL, ISRAEL–During the afternoon Yoav and I drove to the center of this magnificent erosional crater to visit familiar sites and do some preliminary surveys. It was deliciously hot and dry — just the way I like it. I concentrated on the middle of the Matmor Formation, a Jurassic (Callovian) unit of limestones and marls loaded with diverse fossils. I scoped out the sites I want to measure, describe and sample in the next few days. It was fun to see those places where several Wooster students did their Independent Study fieldwork over the years, and to make plans for the next set.

Makhtesh Gadol looking from the Matmor Hills near the center to the north.  The outcrop in the foreground has yielded wonderful fossils from the middle of the Matmor Formation.

Makhtesh Gadol looking from the Matmor Hills near the center to the north (N30.93458°, E34.97387°). The outcrop in the foreground has yielded wonderful fossils from the middle of the Matmor Formation.

This is a fossil coral which was bored by bivalves while it rested on a Jurassic seafloor.  You can see two of the boreholes clearly on the right.  The coral shows compound growth.  Apparently the lower one was shifted to a position almost at right angles from its original orientation, and then it budded off the capping portion on the right.

This is a fossil coral which was bored by bivalves while it rested on a Jurassic seafloor. You can see two of the boreholes clearly on the right. The coral shows compound growth. Apparently the lower one was shifted to a position almost at right angles from its original orientation, and then it budded off the capping portion on the right.

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