CU News
News from the University of Colorado in Boulder.
CU study: Lowly worms survive asteroid wipeout
Oct 10th

While the focus on the so-called K-T boundary extinction is often on the survival and proliferation of mammals, paleo-botanical studies show some of the earliest terrestrial ecosystems to emerge were dominated by low-diversity and opportunistic aquatic plants, said University of Colorado Boulder geological sciences Associate Professor Karen Chin. And while sediments laid down immediately following the impact event generally have relatively few animal fossils, new evidence from North Dakota shows networks of crisscrossing burrows less than three inches above the K-T boundary layer.
“Fossil burrows provide direct evidence of animal activity that occurred right at that spot, and these burrows are quite extensive,” said Chin, who said their characteristics suggest they were probably produced by worms. “To my knowledge, such burrows haven’t been documented in terrestrial environments this close to the K-T boundary. This is a glimpse of a world we don’t know very much about yet.”
While Chin and her colleagues are still working to understand the timing of the fossil burrows as they relate to the K-T extinction boundary, Chin said she believes that they likely were made within a few thousand years after the extinction event. Future studies should help narrow that window, said Chin, who also is curator of paleontology at the University of Colorado Museum of Natural History.
Chin gave a presentation on the new findings at the 2011 annual meeting of the Geological Society of America being held this week in Minneapolis. Co-authors on the study were A.A. Ekdale of the University of Utah and Dean Pearson of the Pioneer Trails Regional Museum in Bowman, N.D.
The three-dimensional burrows were found at the interface of a layer of coal and a layer of siltstone in southwestern North Dakota by Pearson, who has spent many years studying K-T boundary sites in the state. The decomposing organic matter in the ancient environment would have provided a food source for the worms. A few of the burrows were topped by a thin layer of coal, suggesting that the underlying coal may contain additional, earlier worm burrows that are not readily apparent, Chin said.
The clay boundary layer laid down at the end of the Cretaceous Period is associated with high levels of iridium, an element rare in Earth’s crust but abundant in asteroids. The Manhattan-sized asteroid plowed into Earth at 150 times the speed of a jet airliner and is thought to have released about a billion times more energy than the Hiroshima atomic bomb, triggering tremendous dust and ash storms, wildfires, tsunamis, mega-earthquakes and dark, cold “nuclear winter” conditions for a time.
The North Dakota fossil worm burrows indicate the creatures probably were about the diameter of an average earthworm. The burrows indicate horizontal rather than vertical movement through the substrate, likely reflecting feeding activity, Chin said.
The study indicates the burrows were made in a peat-producing, bog-like environment that eventually was buried by sediment. Chin said the worms must have been capable of withstanding the challenging environmental stresses of flooded habitats, including prolonged inundation, low oxygen and acidic conditions.
Since the ancient burrows were filled by sediment, they actually are “positive casts” of the trails made by the worms. The burrows are examples of “trace fossils,” which also include tracks and fossilized feces, or coprolites. “When we reconstruct past environments, soft-bodied animals like worms get short-shrift since they don’t stand out in the fossil record like animals with mineralized skeletons,” said Chin. Ekdale, an expert on trace fossils, was key in analyzing the worm burrows, Chin said.
Chin said extensive work on plant fossils both before and after the K-T boundary event by Denver Museum of Nature and Science Chief Curator Kirk Johnson and his colleagues helped Chin and her research team to characterize the environment inhabited by the burrowers. Johnson’s research helped establish that terrestrial plants suffered heavy losses during the K-T extinction event, as did non-avian dinosaurs and many other terrestrial and marine organisms.
The K-T boundary commonly refers to the dividing line between the Cretaceous and Tertiary periods. Geologists now refer to it as the Cretaceous-Paleogene, or K-Pg boundary event. While a number of vertebrates survived the event — including birds, snakes, lizards, turtles, fish and small mammals — fossil burrows provide direct evidence of animal activity that skeletal fossils cannot show, said Chin. “The fact that the burrows are so close to the K-T boundary is one reason they are so exciting.”
-CU-
CU begins counseling online Boulder
Oct 6th

CU EXPANDS MENTAL HEALTH SERVICES
WITH INTERACTIVE ONLINE SCREENINGS
The University of Colorado Boulder next week will become the first campus in the state to offer the Interactive Screening Program, allowing students to screen their mental health online and anonymously with support from a counselor.
The program rollout on Oct. 9 comes three days after National Depression Screening Day, and after a pilot of the initiative was held last spring on campus.
The Interactive Screening Program was developed specifically for college students by the American Foundation for Suicide Prevention and will be administered at CU-Boulder by Counseling and Psychological Services.
“Some of our most distressed students aren’t necessarily coming in for support,” said CU-Boulder Suicide Prevention Coordinator Amy Robertson. “Part of what’s making it hard for them to seek treatment is a sense of hopelessness. This well-tested national program addresses that barrier and innovatively uses technology as a bridge for students to our services.”
Campus mental health professionals initiate the interactive screenings by identifying groups of potentially at-risk students and e-mailing them invitations to complete a 10-minute questionnaire. A counselor then sends the screening results to the respondent with a personalized message.
“When issues that are particularly distressing — like suicidal thoughts, substance abuse, eating disorders or relationship problems — emerge from the screening, we may inform the student about our services or offer an appointment,” said Robertson. “If they’re not ready, we continue a dialogue with them.”
During the CU-Boulder pilot of the Interactive Screening Program, Robertson targeted students who were on academic probation and e-mailed 225 invitations. More than 20 people, or about 10 percent of the group, filled out the survey — a response rate that is on par with national averages when it comes to depression screenings.
Robertson says CU-Boulder’s Counseling and Psychological Services will use what it learns over time from the program to expand its outreach to potentially at-risk students, including other groups that might feel isolated such as first-year, transfer and graduate students. The screening process will be initiated every two to four weeks.
The Interactive Screening Program is in place at 30 college and university campuses across the nation including the Massachusetts Institute of Technology and Cornell University.
Symptoms of depression can include:
— Persistent sad, anxious or empty mood
— Feelings of guilt, worthlessness or helplessness
— Loss of interest or pleasure in ordinary activities
— Difficulty concentrating or making decisions
— Restlessness or irritability
— Inability to sleep or sleeping too much
— Changes in appetite or weight
— Unexplained aches and pains
“If you are feeling suicidal, or need to get help for a friend who is feeling suicidal, contact CU-Boulder’s Counseling and Psychological Services,” said Robertson. Walk-in hours are held from 10 a.m. to 4 p.m., Monday through Friday. Support by phone also is available 24 hours a day, seven days a week and can be accessed by calling 303-492-6766. If it is after hours, dial “2” to be connected with a mental health professional.
CU-Boulder students are eligible for up to six free sessions per academic year through Counseling and Psychological Services.
For more information on CU-Boulder’s Counseling and Psychological Services visit https://counseling.colorado.edu/.
CU team discovers ancient road
Oct 5th
CU-BOULDER TEAM DISCOVERS ANCIENT ROAD AT MAYA
VILLAGE BURIED BY VOLCANIC ASH 1,400 YEARS AGO
A University of Colorado Boulder-led team excavating a Maya village in El Salvador buried by a volcanic eruption 1,400 years ago has unexpectedly hit an ancient white road that appears to lead to and from the town, which was frozen in time by a blanket of ash.
The road, known as a “sacbe,” is roughly 6 feet across and is made from white volcanic ash from a previous eruption that was packed down and shored up along its edges by residents living there in roughly A.D. 600, said CU-Boulder Professor Payson Sheets, who discovered the buried village known as Ceren near the city of San Salvador in 1978. In Yucatan Maya, the word “sacbe” (SOCK’-bay) literally means “white way” or “white road” and is used to describe elevated ancient roads typically lined with stone and paved with white lime plaster and that sometimes connected temples, plazas and towns.
The sacbe at the buried village of Ceren — which had canals of water running on each side — is the first ever discovered at a Maya archaeology site that was built without bordering paving stones, said Sheets. The road was serendipitously discovered by the team while digging a test pit through 17 feet of volcanic ash in July to analyze agricultural activity on the edges of Ceren, considered the best preserved Maya village in Central America.
“Until our discovery, these roads were only known from the Yucatan area in Mexico and all were built with stone linings, which generally preserved well,” said Sheets of CU’s anthropology department. “It took the unusual preservation at Ceren to tell us the Maya also made them without stone. I’d like to say we saw some anomaly in the ground-penetrating radar data that guided us to the Ceren sacbe, but that was not the case. This was a complete surprise.”
The sacbe was struck almost dead-on by the excavators of the 3-meter by 3-meter test pit, said Sheets, with the full width of road visible. In order to follow the sacbe, two subsequent test pits were excavated to the north and confirmed the sacbe had a minimum length of at least 148 feet long — about half the length of a football field.
The sacbe appears to be headed toward two Ceren ceremonial structures less than 100 feet away — buildings that were unearthed in Ceren by Sheets and his team in 1991. One structure is believed to have been used by a female shaman. The adjacent community ceremonial structure contained evidence — including the bones of butchered deer, a deer headdress painted red and blue and a large alligator-shaped pot — that large quantities of food and drink were being prepared and dispensed to villagers in the town plaza during what Sheets believes was a crop-harvesting ceremony.
“We know there was a celebration going on when the eruption hit,” said Sheets. “And we’ve found no evidence of anyone going back to their houses, gathering up valuables, and fleeing, because all the household doors were tied shut. We think people may have left the plaza and run south, possibly on the sacbe, because the danger was to the north.”
Radiocarbon dates from Ceren indicate the eruption occurred in roughly A.D. 630, and CU researchers have even pinpointed the month and time of day the fiery mass of ash and debris from the Loma Caldera volcano rained down on the town from less than a third of a mile away. Sheets believes the eruption hit at roughly 7 p.m. on an August evening because of the mature corn stalks preserved in ash casts, the fact that the farming implements had been brought inside, the sleeping mats had not yet been rolled out, meals had been served but the dishes were not yet washed, and corn was set into pots to soak in water overnight.
Sheets said it is logical that the villagers in the plaza might have used the white sacbe as an emergency route to flee the destruction of the volcano in the dark of night. “How far they might have gotten, I don’t know,” said Sheets. “It would have been a footrace. I think it is very likely we will find bodies as we follow the sacbe southward in future excavations.” To date, no human remains have been found at the village.
Sacbeob, the plural of sacbe, had strong practical, political and spiritual connotations in the Pre-Columbian Yucatan, said Sheets. Some were fairly long — up to 40 miles — while others stretched less than 50 feet. Because of the high level of preservation at Ceren, the researchers can see hand marks of farmers who were repairing the edges of the sacbe.
While there is speculation the Ceren sacbe may have led to the Maya center of San Andres roughly three miles to the south, there is no evidence of that yet, Sheets said.
While some refer to Ceren as “The New World Pompeii,” Sheets is quick to point out the differences. Pompeii was an affluent Roman resort community with multi-story concrete houses, stone streets and marble statues, while Ceren was a modest farming community. Because tiny particles of hot, moist ash blanketed Ceren and packed the thatch-roofed structures, gardens and agricultural fields, the preservation of organic materials is greater than at Pompeii, where dry, pea-sized particles rained down in the Mount Vesuvius eruption of A.D. 79.
Sheets has visited Pompeii, and researchers from Pompeii have visited Ceren, analyzing the similarities and differences at the sites. “When they tell me they wish they had this kind of preservation level at Pompeii, I tell them I wouldn’t mind finding a marble statue or two at Ceren,” said Sheets.
The Ceren preservation is so great that researchers have found marks of finger swipes in ceramic bowls, human footprints in gardens hosting ash casts of plants like corn and manioc, thatched roofs, woven baskets and pots filled with beans. Researchers have found the remains of mice that lived in the thatched roofs of kitchen areas, and entomologists have even been able to discern that two species of ants inhabited the village, Sheets said.
While much of the Maya archaeological record points to rigid, top-down societies where the elite made most political and economic decisions, there is evidence of some autonomy at Ceren, including divergent choices by farmers regarding crop cultivation techniques that were discovered this summer, said Sheets. He believes a community building with two large benches in the front room may have hosted village elders when it came time to make community decisions at Ceren.
In addition to Sheets, the 2011 team included CU-Boulder graduate students Christine Dixon, Alexandria Halmbacher and Theresa Heindel, University of Cincinnati Professor David Lentz, University of Cincinnati graduate student Christine Hoffer, Celine Lamb from the Sorbonne in Paris and 23 local Salvadoran workers. The 2011 field season was funded by the National Science Foundation.
“Students on the project are essential,” said Sheets. “They put up with less than ideal living conditions and they do valuable work, sometimes pursuing their own research paths based on discoveries they make at the site.” Since 1978, more than 30 undergraduate and graduate students have worked under Sheets at Ceren, including 14 who have received or are pursuing master’s or doctoral degrees.
“When I first heard about Ceren, I immediately wanted to know more,” said master’s degree candidate Theresa Heindel, who came to CU-Boulder after graduating from the University of Wisconsin-Madison and who spent the 2011 field season assessing crop cultivation in Ceren’s agricultural fields that were frozen in time by ash. “We don’t see this type of cultivation anywhere in Central America, and we don’t see this level of preservation anywhere in the world.”
In 2009 Sheets and his team discovered a previously unknown Maya agriculture system at Ceren — intensively cultivated manioc fields that yielded at least 10 tons of manioc shortly before the eruption 1,400 years ago. It was the first and only evidence of intense manioc cultivation at any New World archaeology site and Sheets and others believe such large manioc crops could have played a vital role in feeding indigenous societies living throughout tropical Latin America, he said.
Sheets has collaborated with the National Science Foundation, the National Geographic Society, the Smithsonian Institution, the Getty Conservation Institute and a number of universities since 1978. The 10-acre Joya de Ceren Archaeological Park was declared a UNESCO World Heritage Site in 1993.
“When the radiocarbon dates on the thatched roofs came back in 1978, I saw the rest of my professional life. I knew I did not need to look for any more new archaeological sites,” said Sheets. “There is well over a century of research still to be done at Ceren — in some ways we’ve only scratched the surface.”
A video news story on Ceren is available by going to http://www.colorado.edu/news/ and clicking on the story headline.
-CU-