Tree rings, Lake Erie, and climate change are the topics of a recent NPR interview with Wooster’s own Greg Wiles. Greg and his research group have been making headlines for their study that suggests natural climate variability plays a role in controlling changes in Lake Erie’s level. Stay tuned for more developments from Wooster’s Tree Ring Lab!
From the Guardian, May 14, 2009 issue.
MITZPE RAMON, ISRAEL–After today’s work near Makhtesh Ramon, our fieldwork is over for this season. This evening I pack up our collections in my luggage, have a last dinner with Yoav and his family in their desert home, and then get some sleep before a very early departure tomorrow morning. I am looking forward to returning soon with Wooster Independent Study students to continue our work in the Mesozoic rocks of southern Israel.
A Bronze Age tumulus (rock-covered grave) at the top of a hill north of Makhtesh Ramon.
MAKHTESH RAMON, ISRAEL–On my last day of fieldwork Yoav took me to some wonderfully complex exposures of Cretaceous and Tertiary rocks just north of Makhtesh Ramon. They tell a story of the origins of the Makhtesh anticlinal structure, especially the date it appeared and whether it was ever exposed as an island before its center was eroded away. Part of the debate comes down to the depth at which certain Santonian (Cretaceous) sediments were deposited. These sediments contain oysters and exquisite shark’s teeth. We collected a nice set (see below) which I will attempt to identify to see if we can use what we may know about these sharks to determine the depth of deposition.
Cretaceous shark teeth collected from just north of Makhtesh Ramon (N30.56235°, E34.64876°).
Another indication of how shallow the seas were in the Middle Jurassic of southern Israel. This bedding plane in the Matmor Formation of Makhtesh Gadol has a gastropod (snail) fossil in the center of the image surrounded by angular shells of fossil mytilids (clams commonly called mussels today). In life the mytilids had attached to the gastropod and each other by fine yet strong byssal thread produced by a special gland. This kind of relationship is very common in tidal pools and other shallow areas where wave action is strong.
MAKHTESH GADOL, ISRAEL–One of the goals of this trip to the Negev was to map and analyze a series of faults Wooster geology students and Yoav Avni have found during our five years of fieldwork in Makhtesh Gadol. Our projects have all been stratigraphic and paleontological, and we need to understand the structural framework of these rocks before we can interpret their histories. In turn the faults could only be assessed after the stratigraphy has been sorted out, which we have essentially done now. Yoav and I were able then to examine these faults this week and place them on the map with some ideas about their dimensions and times of movement. (“Yoav and I” means in this case that I watched Yoav do the real work!)
Vertical fault (at the hammer head) in the Matmor Formation, Makhtesh Gadol, Israel.
Most of the faults are vertical and more or less east-west trending. After mapping them, the fun part was working out how much displacement took place and when. For example, using a Lower Cretaceous laterite as a key horizon, we could tell on one segment of a fault that 6.5 meters of displacement was prior to laterite formation and 4.5 meters came after the laterite. This could only be done after the stratigraphy of the Jurassic units under the laterite was described, which is Wooster’s contribution to this structural analysis.
Note the curly worm tubes and borings made by another type of worm. There are also tiny little sponges in this view, and even tinier brachiopods. This is a "cryptic community", meaning it lived in a protected space, in this case on the underside of a coral colony just above the sea floor. The study of cryptic marine communities and their evolution has been a speciality of the Wooster paleontology lab. (Matmor Formation, Jurassic, Makhtesh Gadol.)
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.
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.
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.
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.
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°.
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.
