Mark Wilson March 13th, 2011
Tsunami bearing down on a Japanese village (March 11, 2011). From the Associated Press.
HORONOBE-CHO, HOKKAIDO, JAPAN–I am relieved to report that my friend and fellow Wooster Geology classmate Kaz Aoki and his family survived last week’s devastating earthquake and tsunami. Kaz, his wife Sachiko, their four daughters and their new son-in-law all are unscathed, considering themselves “very lucky”. Their previous hometown, Kamaishi-shi was severely damaged. They say a tsunami warning 30 minutes before the event saved many lives.
Kaz is working in crisis mode right now. He is a Principal Senior Scientist in the Japan Atomic Energy Agency (JAEA) at the Geological Isolation Research and Development Directorate. We can only imagine the stress in the face of repeated failures in several nuclear power plants.
The Wooster Geology Department, all four faculty members, our Administrative Coordinator Patrice Reeder, and a group of students are leaving this morning for our field trip in the Mojave Desert. This blog will be filled with fun posts and colorful images, as it should be. We will not forget, though, the current travails of the Japanese people and our particular friends the Aoki family.
Mark Wilson March 13th, 2011
The delicious scallop has a long, long history. Wooster’s variety, known as Aviculopecten subcardiformis, is about 345 million years old. The beauty above was found in the Logan Formation, a conglomeratic sandstone that underlies much of the city, including the college. This particular fossil is preserved as an external mold, meaning the shell is dissolved away and only an impression remains in the surrounding sediment. Note that this preservation is still so good that we can count all the ribs and even growth lines.
Scallops are characterized by a nearly-symmetrical shell. They have extensions along the hingeline (at the top of the image) that are commonly called “ears” and technically termed auricles. They have one large muscle (adductor) used to close the shell. It is relatively large and the part of the clam we find so tasty.
Pecten jacobaeus from the Mediterranean Sea. (Photo courtesy of Andreas Tille of en.wikipedia.)
Many modern scallops use that large adductor muscle to clap the valves together when they are threatened, enabling them to swim short distances. As an early warning system to detect predators (including us, I suppose), they have rows of tiny eyes in the soft tissue around the edge of the shell (see below).
The eyes of this living scallop are the small bluish spheres along the edge of the mantle.
We can’t tell if our ancient scallop was able to see its enemies and swim away. It does, though, take us back to a time when a warm shallow sea covered our little patch of Ohio.
mpollock March 11th, 2011
As Dr. Wilson so gleefully pointed out today, the last several blog posts have been about fossils. I think it’s about time for a change of subject, don’t you?
Spring break officially begins tomorrow, and this is what Wooster looks like tonight:
A view of the snow covered street from my living room. I had to take the picture tonight because Dr. Wilson would have undoubtedly beat me to it in the morning.
The Wooster Geologists are ready to leave all of the snow behind! In a few short days, we’ll be headed to the warm and sunny Mojave Desert. The Desert Studies Center will serve as our base camp while we explore Death Valley, the Mojave National Preserve, and Barstow, CA (Dr. Wilson’s hometown). We invite you to follow us on our week-long adventure. Be on the lookout for posts that feature blue skies, stunning vistas, and geologists learning about the desert through direct experience. (It’s good to be a geologist.)
Mark Wilson March 6th, 2011
T=thecideide brachiopod; B=cyclostome bryozoans; S=sabellid worm tubes; g=gonozooids on one of the cyclostome bryozoans.
This delightful little community is the subject of a current research project that developed from Independent Study fieldwork in 2006. Elyse Zavar (’07) and I traveled to southern Poland to work on Jurassic fossils associated with a carbonate hardground at the Callovian-Oxfordian boundary near the village of Zalas (the link goes to Elyse’s photographs). With our Polish colleagues we found complex stratigraphy and an even more complex set of fossils. Now Elyse (a graduate student in the great state of Texas) and I have joined with Michał Zatoń of the University of Silesia in Sosnowiec, Poland, and submitted a manuscript describing and interpreting the sclerobionts (hard substrate dwellers) on the large limid bivalve Ctenostreon proboscideum. Michał is the lead author because of his long experience with these fossils and the complicated stratigraphy.
The hardground complex in the Zalas Quarry, southern Poland. It is Callovian below the blade of the well-traveled hammer and Oxfordian above (both stages of the Jurassic).
I have a soft spot for thecideide brachiopods, so they’re the stars of this show for me. I’ve come across them on Jurassic hard substrates many times, so they are old friends. They are filter-feeders like their larger brachiopod cousins, but they cemented one valve to a shell or rock for stability. The bryozoans in this community are also fun, especially when they have gonozooids as imaged above. A gonozooid is a specialized zooecium for brooding eggs and larvae. They are sometimes the only diagnostic features on sheet-like cyclostome bryozoans. There are plenty of serpulid and sabellid worm tubes as well, along with occasional oysters, calcareous sponges, and borings.
A sabellid worm tube and other encrusters.
We are comparing this Polish Jurassic community to others of the same time interval around the world. Curiously and probably not by chance, a similar sclerobiont assemblage is found in the Middle Jurassic of southern Israel — the subject of another Wooster study.
An encrusting oyster.