Sentences with phrase «dating ice samples»

«Also, dating ice samples is not definitive.»

Not exact matches

Ice core samples from Quelccaya are especially unique because they can be annually dated, Thompson says.

The researchers determined from the isotope ratio that the Taylor Glacier samples were 120,000 years old, and validated the estimate by comparing the results to well - dated ice core measurements of atmospheric methane and oxygen from that same period.

Sampling 7,000 - year - old ice cores as well as snowpack dating from 1969 through the mid-1990s, Barbante's team found that concentrations of the metals had risen almost sevenfold since the mid-1970s, when catalytic converters first came into widespread use.

The amount and type of genetic material, along with carbon dating of the samples, reveal that between 50,000 and 25,000 years ago — before the peak of the last ice age — arctic vegetation consisted mainly of forbs, the researchers report today in Nature.

In ice core studies, the accurate and precise dating of the core samples is a central issue that must be investigated to better constrain the timing, sequence, and duration of past climatic events.

As presented, the data has been processed and expressed in a user - friendly geo - spatial graphic showing the ice - out dates for a sampling of lakes of a given year.

Uncertainties should decrease closer to near - current dates (e.g. from denser and more accurate sampling)-- but note that these products also employ different QC and analysis methods, rely to varying degrees on satellite data, on sea - ice data to constrain polar SST, and on bias adjustments for historical changes in measurement methods.

There is a difference between the lag of gas age after ice age dating and the resolution of the gas sampling.