Geosciences

Congratulations Williams College Class of ’13 Geosciences Graduates!

Inez Tan — Tue, 04 Jun 2013 20:33:53 +0000

Congratulations to the Williams College Geosciences Class of 2013!

Bryce Mitsunaga, Ian Nesbitt, Tommy Gaidus, Johnny Ray Hinojosa, Leaf Elliott, Gabe Lewis, Miranda Bona, Sarah Rowe, David Rapp, Claudia Corona.

Upcoming Events for the Month of April 2013

Ahmad Greene-Hayes — Tue, 02 Apr 2013 18:08:08 +0000

Monday, April 8

Rewarding Geosciences Careers: Environmental Engineering

Matt Art ’00, Senior Scientist with e4sciences

Noon, Clark Hall, Room 105

Pizza lunch will be provided!

Thursday, April 11

Geosciences Dept. Class of 60′s Lecture Series

Dr. Sara Pruss, Smith College

“Life After Snowball: A New Record of Eukaryotes from the Neoproterozoic of Namibia

4:15 pm, Clark Hall, Room 204

Monday, April 15

Lauren Interess Fellowship Presentation

Will Wicherski ’14

“Cause and Consequences of Norwegian Oil”

Noon, Clark Hall, Room 204

Pizza lunch will be provided!

Wednesday, April 24

Consortium for Ocean Leadership 2012-2013 Distinguished Lecturer Series

Dr. Brandon Dugan, Rice University

Origin, Evolution, and Impacts of Large Submarine Landslides

4:15 pm, Clark Hall, Room 204

Monday, May 13

Senior Thesis Presentations

Time and titles TBA

Tiny organisms a giant discovery for Williams College professor

Ahmad Greene-Hayes — Wed, 13 Feb 2013 22:28:49 +0000

By Scott Stafford, Berkshire Eagle Staff

February 10, 2013

WILLIAMSTOWN — Phoebe Cohen is a detective, of sorts. She’s examining clues from the scene of a series of attacks by predators. Problem is, the clues are getting old — more than 750 million years old.Cohen, 32, an assistant professor of geosciences at Williams College, is a paleontologist and educator. In 2007, while working towards her PhD at Harvard University, she and her research team discovered evidence of predatory behavior in a Yukon field of geological samples from the Neoproterozoic era that are between 717 to 812 million years old — which is even before the evolution of animal life.The samples contained the fossilized remains of single-cell organisms that populated the oceans of the time.Using a new take on a scientific technique that frees larger fossils from rocks, Cohen’s team used mild acid to dissolve the carbonate rock material to uncover the microscopic fossils of hundreds of ancient organisms less than 10 microns across, or one-tenth the diameter of a human hair. Until she looked in the microscope she had no idea what she would see.

“There’s nothing cooler than looking in a microscope and seeing a fossil no one else has ever seen before,” she said.

The samples showed that these organisms were able to form shield plating through biomineralization — somewhat like exoskeletons — that survived the eons long after the single-cell host had dissolved. The plate-armor weighed down the hosts, which sank to the bottom of the ocean to be trapped in sediment. Tectonic activity eventually propelled some of that sedimentary rock to the planet’s surface near the peaks of a mountain range along the western border of the Yukon, a province in northwestern Canada.

Cohen said the development of the tiny armor plating is likely in response to external threats, such as predatory danger. She noted that this is the earliest evidence of predatory and defensive behavior in the single cell organisms — which likely had an early influence in the evolutionary cycle of life on Earth.

“As far as we can tell, these are the first organisms to show evidence of using minerals to make hard parts, a behavior that is very common in today’s environment,” she said. “It’s also probably the first evidence of predation, which has played a very important role in the evolution of animal life.”

According to a colleague, Sara Pruss, an assistant professor of geosciences at Smith College in Northampton, Cohen’s work “changes the way we think about ecology of the Neoproterozoic, because it is possible that skeleton-building indicates some need for protection, either from predators or the environment. This is a dramatic shift in how we have thought about biomineralization and has opened up new windows of exploration.”

Another associate, Susannah M. Porter, associate director of the Earth Research Institute at the University of California at Santa Barbara, said Cohen’s conclusions were surprising.

“These fossils represent not only the first good evidence for mineralized skeletons in eukaryotes, they also represent a rather unusual choice of mineral for a protist,” she said.

Cohen’s work had the additional value of bringing a new technique to the field of Precambrian paleontology that will allow scientists to discover microscopic relics in new areas that may be encased in different kinds of rock.

“Some of Phoebe’s fossils were found in acid-resistant residues of limestone, which is a common sedimentary rock formed in tropical environments,” Pruss said. “This type of rock has only rarely been examined for fossils in the Neoproterozoic, so Phoebe’s work also broadened the way paleontologists search for fossils.”

“In terms of new avenues of research,” Porter noted, “this work has highlighted the potential of looking in carbonate rocks for fossils of early life. In the past, Precambrian micropaleontologists have focused on [shales and fine-grained silica] rock types and have pretty much ignored carbonates. We won’t do that any more.”

With part of Cohen’s case solved, there is much more to do to establish the vast timeline of evolution and its early connections to modern life forms.

Last summer, Cohen and a research team went back to the Yukon to a spot a few miles east of the 2007 site. They were able to establish that the fossils were not present in that area.

This summer, Cohen said, she hopes to return to the original site to re-establish the presence of the fossils and to expand on the research and on the variety of samples gathered. It may not be action-packed — there will not likely be a TV show called CSI: Neoproterozoic — but for Cohen, it will be thrilling and could certainly be illuminating.

“It’s still quite a mystery,” she said. “For example, what was so special about that one spot? We haven’t stopped looking.”

To reach Scott Stafford:
sstafford@berkshireeagle.com,
or (413) 496-6241.
On Twitter: @BE_SStafford

Source: The Berkshire Eagle

Glaciation, Extinction, and Microbes: Sulfur Isotopes from the Ordovian-Silurian Boundary

Ahmad Greene-Hayes — Wed, 13 Feb 2013 22:11:32 +0000

Dr. David Jones from Amherst College will be here Thursday Feb. 21 to give a talk on “Glaciation, Extinction, and Microbes: Sulfur Isotopes from the Ordovian-Silurian Boundary.” The Lecture begins at 4:15 pm in Clark Hall, Room 204. Refreshments available at 4:00 pm in the Geosciences Common Room. All are welcome!

Learn more about Professor Jones, here.

Phoebe Cohen discovers 750-million-year-old fossil

Ahmad Greene-Hayes — Sun, 06 Jan 2013 16:57:17 +0000

A 750-million-year-old fossil discovered by geoscientist Phoebe Cohen may hold clues to how life has changed the earth—and vice versa.

Following up on work done by scientists in the 1970s, Cohen and a fellow Harvard University graduate school student traveled to the Yukon in 2007 to study rock formations and found a veritable goldmine of fossil-containing rock. Advancements in scientific tools and instruments in the last 40 years allowed Cohen to examine the fossils in a new way, by dissolving the carbonate rock in acetic acid rather than looking at a sliver or cross-section of the rock, as had been done in the past.

“After the carbonate dissolves away, what’s left is organic matter,” says Cohen, now an assistant professor in the Geosciences Department. And what she was able to see in the organic matter amazed her: three-dimensional “bones” of what might be one of the earth’s first eukaryotic single-celled organisms to make hard parts.

Eukaryotic cells have a nucleus and organelles, like animal and plant cells but unlike bacteria cells. The fossil Cohen discovered, which she named Quadrireticulum palmaspinosum (loosely translating to “four-sided net with palm tree spine”), measures about one-tenth the width of a human hair.

Why did a creature so tiny need bones? Cohen’s theory is that at a certain point in history, single-celled organisms needed to “biomineralize”—or create a type of exoskeleton—in order to protect themselves from being eaten by other single-celled organisms. Later, these biomineralized organisms, weighed down by their hard parts, sank to the bottom of the ocean.

As the organisms became buried in sediment, the carbon they contained was locked away with them, reducing the levels of carbon in the ocean and the atmosphere. Over the next 750 million years they developed into the giant rock in the Yukon that Cohen studied. The process may have caused the earth to cool, perhaps eventually contributing to what Cohen and other scientists call “a snowball earth event,” when ice covered the entire planet for millions of years.

With the help of research assistants Nakita VanBiene ’15, who is a geoscienes major, and Kim Kiplagat ’16, Cohen is now studying snowball earth events. She’s in the process of writing a grant proposal to research the time periods before, during, and just after the two major snowball earth events in our planet’s history, which took place 717 million and 635 million years ago, to better understand the relationships between evolutionary events such as biomineralization and events in the earth system such as climate change.

“This work helps us understand how life has evolved through time, in response to both other living things and to the environment,” Cohen says. “We are working toward a better understanding of the dynamics between evolution and changes in the earth’s climate over geologic time scales.”

Click the image above to see a larger version.

From: http://www.williams.edu/feature-stories/climate-change-on-a-geologic-scale/

Rónadh Cox featured on Williams Thinking

Ahmad Greene-Hayes — Mon, 16 Jul 2012 18:46:50 +0000

Boulder Thoughts: Decoding the World through Geoscience

Rónadh Cox, Chair of Geosciences & the Maritime Studies Program, tells you everything you ever wanted to know about decoding the world through geoscience. This correspondent is a fan of the pun that is ‘boulder.’ That’s the power of Williams Thinking right there.

Geosciences faculty explore half-billion-year-old ledge

Inez Tan — Mon, 07 Nov 2011 15:11:31 +0000

Recently, many members of the Geosciences Faculty took a field trip to the Stetson-Sawyer construction site to do what they love – examine rocks. In particular, they were interested in the ledge that has been the subject of great attention and the source of a tremendous amount of noise both on campus and throughout town. Here is what the faculty had to say about the ledge:

“The rock ledge that lies beneath the Stetson-Sawyer building site is mostly quartzite. There are interlayers of micaceous rock (phyllite or schist) that mark old fault zones. The rocks are close to half a billion years old, and record the presence of a shallow, probably warm, ocean in this area. The quartzite is extremely hard. It consists of quartz sand grains (with some carbonate material) that are completely cemented together with silica, and there are almost no joints or fractures in the rock—which explains why it’s such a difficult (and noisy) job to hammer out the building site.”

BBL/Skanska engineer Peter Usher led the tour and took all but the first photo.