PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

New study determines more accurate method to date tropical glacier moraines

Dartmouth-led research may alter previous interpretations of climate's impact on equatorial glaciers

2013-11-19
(Press-News.org) Contact information: John Cramer
john.cramer@dartmouth.edu
603-646-9130
Dartmouth College
New study determines more accurate method to date tropical glacier moraines Dartmouth-led research may alter previous interpretations of climate's impact on equatorial glaciers

A Dartmouth-led team has found a more accurate method to determine the ages of boulders deposited by tropical glaciers, findings that will likely influence previous research of how climate change has impacted ice masses around the equator.

The study appears in the journal Quaternary Geochronology. A PDF of the study is available on request.

Scientists use a variety of dating methods to determine the ages of glacial moraines around the world, from the poles where glaciers are at sea level to the tropics where glaciers are high in the mountains. Moraines are sedimentary deposits that mark the past extents of glaciers. Since glaciers respond sensitively to climate, especially at high latitudes and high altitudes, the timing of glacial fluctuations marked by moraines can help scientists to better understand past climatic variations and how glaciers may respond to future changes.

In the tropics, glacial scientists commonly use beryllium-10 surface exposure dating. Beryllium-10 is an isotope of beryllium produced when cosmic rays strike bedrock that is exposed to air. Predictable rates of decay tell scientists how long ago the isotope was generated and suggest that the rock was covered in ice before then. Elevation, latitude and other factors affect the rate at which beryllium-10 is produced, but researchers typically use rates taken from calibration sites scattered around the globe rather than rates locally calibrated at the sites being studied.

The Dartmouth-led team looked at beryllium-10 concentrations in moraine boulders deposited by the Quelccaya Ice Cap, the largest ice mass in the tropics. Quelccaya, which sits 18,000 feet above sea level in the Peruvian Andes, has retreated significantly in recent decades. The researchers determined a new locally calibrated production rate that is at least 11 percent to 15 percent lower than the traditional global production rate.

"The use of our locally calibrated beryllium-10 production rate will change the surface exposure ages reported in previously published studies at low latitude, high altitude sites and may alter prior paleoclimate interpretations," said Assistant Professor Meredith Kelly, the study's lead author and a glacial geomorphologist at Dartmouth.

The new production rate yields beryllium-10 ages that are older than previously reported, which means the boulders were exposed for longer than previously estimated. Prior studies suggested glaciers in the Peruvian Andes advanced during early Holocene time 8,000 -10,000 years ago, a period thought to have been warm but perhaps wet in the Andes. But the new production rate pushes back the beryllium-10 ages to 11,000 -12,000 years ago when the tropics were cooler and drier. Also during this time, glaciers expanded in the northern hemisphere, which indicates a relationship between the climate mechanisms that caused cooling in the northern hemisphere and southern tropics.

The findings suggest the new production rate should be used to deliver more precise ages of moraines in low-latitude, high-altitude locations, particularly in the tropical Andes. Such precision can help scientists to more accurately reconstruct past glacial and climatic variations, Kelly said.



INFORMATION:



Professor Meredith Kelly is available to comment at Meredith.A.Kelly@dartmouth.edu

The research team included researchers from Dartmouth College, the University of Cincinnati, Pennsylvania State University, New Mexico Institute of Mining and Technology, Columbia University, Ecole Polytechnique Federale de Lausanne, University of Colorado and University of Arizona.

The research was supported by the Gary C. Comer Science and Education Foundation, Lamont Climate Center, and the National Science Foundation.

Broadcast studios: Dartmouth has TV and radio studios available for interviews. For more information, visit: http://www.dartmouth.edu/~opa/radio-tv-studios/



ELSE PRESS RELEASES FROM THIS DATE:

Study finds youth prefer and benefit more from rapid point-of-care HIV testing

2013-11-19
Study finds youth prefer and benefit more from rapid point-of-care HIV testing TORONTO, Nov. 19, 2013 – Youth prefer, accept and receive HIV results more often when offered rapid finger prick or saliva swab tests rather than traditional blood tests according ...

Study: Ureteral injury during robot-assisted prostate surgery

2013-11-19
Study: Ureteral injury during robot-assisted prostate surgery DETROIT – There may be warning signs to help surgeons avoid damaging part of the urinary system during robot-assisted surgical removal of prostate cancer, ultimately preventing the expense of additional ...

Tropical Cyclone 04B forms in northern Indian Ocean

2013-11-19
Tropical Cyclone 04B forms in northern Indian Ocean The fourth tropical cyclone of the Northern Indian Ocean season formed and is headed for landfall in a couple of days in southeastern India. NASA's TRMM satellite saw broken bands of thunderstorms with moderate ...

NASA sees late season subtropical storm Melissa form in Atlantic

2013-11-19
NASA sees late season subtropical storm Melissa form in Atlantic Hurricane Season ends on November 30, and subtropical storm Melissa formed with less than two weeks to go. Melissa formed on Monday, November 18 about 695 miles/1,120 km east-southeast of Bermuda, near ...

HZDR researchers simulate electrons in astrophysical plasma jets

2013-11-19
HZDR researchers simulate electrons in astrophysical plasma jets "When the wind blows over the ocean, waves form," Michael Bussmann, head of a HZDR junior research group, starts to explain. "At high wind speeds, water and wind swirl about one ...

Social values vary across Canada

2013-11-19
Social values vary across Canada New survey led by Concordia University sheds light on responsible citizenship This news release is available in French. Montreal, November 19, 2013 — Canada: true north, strong and free. But how strong are our beliefs? ...

Demand for details on food labels includes the good -- and the bad

2013-11-19
Demand for details on food labels includes the good -- and the bad ITHACA, N.Y. – It's no surprise that labels are becoming the "go to" place when people have questions about how food is produced. But new Cornell University research finds that consumers crave more information, ...

New study reports on the high cost of cardiac surgery healthcare associated infections

2013-11-19
New study reports on the high cost of cardiac surgery healthcare associated infections Findings reported at AHA Scientific Sessions 2013 reveal the economic impact of HAIs following cardiac surgery After cardiac surgery, ...

Preschoolers can learn lasting heart-healthy lessons

2013-11-19
Preschoolers can learn lasting heart-healthy lessons Research team led by Dr. Valentin Fuster, Director of Mount Sinai Heart at The Mount Sinai Hospital, present promising 3-year follow-up study results in late-breaking clinical ...

LVAD patients benefit from heart injection with millions of powerful cells

2013-11-19
LVAD patients benefit from heart injection with millions of powerful cells New study results presented at AHA Scientific Sessions 2013 show a single dose of stem cell therapy during surgery may improve new LVAD patients' heart ...

LAST 30 PRESS RELEASES:

Thirty-year mystery of dissonance in the “ringing” of black holes explained

Less intensive works best for agricultural soil

Arctic rivers project receives “national champion” designation from frontiers foundation

Computational biology paves the way for new ALS tests

Study offers new hope for babies born with opioid withdrawal syndrome

UT, Volkswagen Group of America celebrate research partnership

New Medicare program could dramatically improve affordability for cancer drugs – if patients enroll

Are ‘zombie’ skin cells harmful or helpful? The answer may be in their shapes

University of Cincinnati Cancer Center presents research at AACR 2025

Head and neck, breast, lung and survivorship studies headline Dana-Farber research at AACR Annual Meeting 2025

AACR: Researchers share promising results from MD Anderson clinical trials

New research explains why our waistlines expand in middle age

Advancements in muon detection: Taishan Antineutrino Observatory's innovative top veto tracker

Chips off the old block

Microvascular decompression combined with nerve combing for atypical trigeminal neuralgia

Cutting the complexity from digital carpentry

Lung immune cell type “quietly” controls inflammation in COVID-19

Fiscal impact of expanded Medicare coverage for GLP-1 receptor agonists to treat obesity

State and sociodemographic trends in US cigarette smoking with future projections

Young adults drive historic decline in smoking

NFCR congratulates Dr. Robert C. Bast, Jr. on receiving the AACR-Daniel D. Von Hoff Award for Outstanding Contributions to Education and Training in Cancer Research

Chimpanzee stem cells offer new insights into early embryonic development

This injected protein-like polymer helps tissues heal after a heart attack

FlexTech inaugural issue launches, pioneering interdisciplinary innovation in flexible technology

In Down syndrome mice, 40Hz light and sound improve cognition, neurogenesis, connectivity

Methyl eugenol: potential to inhibit oxidative stress, address related diseases, and its toxicological effects

A vascularized multilayer chip reveals shear stress-induced angiogenesis in diverse fluid conditions

AI helps unravel a cause of Alzheimer's disease and identify a therapeutic candidate

Coalition of Autism Scientists critiques US Department of Health and Human Services Autism Research Initiative

Structure dictates effectiveness, safety in nanomedicine

[Press-News.org] New study determines more accurate method to date tropical glacier moraines
Dartmouth-led research may alter previous interpretations of climate's impact on equatorial glaciers