Wooster Geologists

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.

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.

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!

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 (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.

MAKHTESH RAMON, ISRAEL–As part of a mine reclamation project in the Makhtesh Ramon National Park near Mitzpe Ramon, the ranger noticed large pieces of fossilized wood coming from the tailings of a bauxite mine which were being trucked to fill large excavations.  Rather than bury these specimens forever, he called the Geological Survey to take a look.  Yoav Avni, one of my Israeli colleagues and a good friend, took me there this morning to see the fossils and help remove them from the debris piles.

Examining pieces of Jurassic tree trunks with the Makhtesh Ramon ranger (center).

The wood is from the lower part of the Ardon Formation, a Jurassic unit lying unconformably on Triassic sediments.  The forest was on the equator during the Early Jurassic, which could make it significant.  Most of the wood is coalified, with some patches of silicification.  We’ll take samples to the Geological Survey headquarters in Jerusalem on Sunday to examine them more closely.  This was a fun little detour because I’ve never seen Jurassic coal — nor had a front-end loader help me sort out specimens!