Share shares ‘There are findings in our study that could suggest that stopping smoking might allow the brain’s cortex to recover some of its thickness, though we need further studies conducted with repeat measures to test that idea. Heavy ex-smokers in the study who had given up smoking for more than 25 years still had a thinner cortex. Although the cortex grows thinner with normal ageing, the study found that smoking appears to accelerate the thinning process. A thinner brain cortex is associated with adult cognitive decline. The cortex is the outer layer which covers two thirds of the brain’s mass. The cerebral cortex is the outer layer of the brain often referred to as gray matter. It is gray because the nerves in this area lack the insulation that makes other parts of the brain appear white. The cortex covers the outer part of the cerebrum and typically, in a healthy person, measures between 1. It consists of folded bulges that create deep furrows. The folds add to the brain’s surface area and therefore increase the amount of gray matter, and the quantity of information that can be processed.
West Antarctic Ice Sheet
How do ice cores work? Current period is at right. From bottom to top: Milankovitch cycles connected to 18O. From top to bottom: Ice sheets have one particularly special property.
The Big Data of Ice, Rocks, Soils, and Sediments. Inside the material archives of climate science.
Santorini caldera Geological evidence shows the Thera volcano erupted numerous times over several hundred thousand years before the Minoan eruption. In a repeating process, the volcano would violently erupt, then eventually collapse into a roughly circular seawater-filled caldera , with numerous small islands forming the circle. The caldera would slowly refill with magma, building a new volcano, which erupted and then collapsed in an ongoing cyclical process.
The northern part of the caldera was refilled by the volcanic ash and lava, then collapsed again. The volcano ejected up to four times as much as the well-recorded eruption by Krakatoa in The Thera volcanic events and subsequent ashfall probably sterilized the island, i. This layer has three distinct bands that indicate the different phases of the eruption. The thinness of the first ash layer, along with the lack of noticeable erosion of that layer by winter rains before the next layer was deposited, indicate that the volcano gave the local population a few months’ warning.
Ice Frozen form of the water molecule. Ice has a specific gravity 0. This difference in specific gravity causes ice to float on water. Ice Age Period of time when glaciers dominate the landscape of the Earth. The last major Ice Age was during the Pleistocene epoch. Iceberg A mass of ice found floating in the ocean or a lake.
Wintertime Antarctic sea ice is increasing at a small rate and with substantial year-to-year variation. Monthly sea ice data show trends of increasing sea ice extent that are slightly above the mean year-to-year variability over the satellite record ( to present).
Ice-sheet dynamics Sampling the surface of Taku Glacier in Alaska. There is increasingly dense firn between surface snow and blue glacier ice. An ice core is a vertical column through a glacier, sampling the layers that formed through an annual cycle of snowfall and melt. At Summit Camp in Greenland, the depth is 77 m and the ice is years old; at Dome C in Antarctica the depth is 95 m and the age years. The bubbles disappear and the ice becomes more transparent. Ice is lost at the edges of the glacier to icebergs , or to summer melting, and the overall shape of the glacier does not change much with time.
These can be located using maps of the flow lines. These include soot, ash, and other types of particle from forest fires and volcanoes ; isotopes such as beryllium created by cosmic rays ; micrometeorites ; and pollen.
Frequently Asked Questions on Arctic sea ice
Free adult sex mobile chat no Cerita bisex In part, they measure the age of rocks and other natural materials by dating techniques. They can date rocks by gauging the amount of decay of radioactive elements. What has so far been discovered with ice core research? In addition, other dating methods using radioactive isotopes and known volcanic horizons can give a precise means of dating the layers.
London’s population of 18th century dragons was tragically wiped out by a mini ice age – and a deadly volcanic eruption. But now, thanks to new technology, the ‘descendants’ of the.
Evidence at Mohenjo-Daro When excavations of Harappa and Mohenjo-Daro reached the street level, they discovered skeletons scattered about the cities, many holding hands and sprawling in the streets as if some instant, horrible doom had taken place. People were just lying, unburied, in the streets of the city. And these skeletons are thousands of years old, even by traditional archaeological standards.
What could cause such a thing? Why did the bodies not decay or get eaten by wild animals? Furthermore, there is no apparent cause of a physically violent death. These skeletons are among the most radioactive ever found, on par with those at Hiroshima and Nagasaki.
Food historians confirm the European practice of topping baked goods most notably pie and cake with rich cream sauce, whipped dates to Renaissance times. Historic cookbooks offer several examples; none of which are titled “a la mode. While the phrase is French, we find no supporting print evidence the combination of ice cream topped dessert originated in that country. Barry Popik, etymolotgist extrodinaire, traces the phrase to the late s. Our survey of historic American newspapers confirms the phrase became popular in the early 20th century.
It has some currency in English in the eighteenth century and nineteeth centuries in the compressed form alamode beef.
Ice cream Food historians tell us the history of ice cream begins with ancient flavored ices. The Chinese are generally credited for creating the first ice creams, possibly as early as BC.
General considerations Distinctions between relative-age and absolute-age measurements Local relationships on a single outcrop or archaeological site can often be interpreted to deduce the sequence in which the materials were assembled. This then can be used to deduce the sequence of events and processes that took place or the history of that brief period of time as recorded in the rocks or soil.
For example, the presence of recycled bricks at an archaeological site indicates the sequence in which the structures were built. Similarly, in geology, if distinctive granitic pebbles can be found in the sediment beside a similar granitic body, it can be inferred that the granite, after cooling, had been uplifted and eroded and therefore was not injected into the adjacent rock sequence.
Although with clever detective work many complex time sequences or relative ages can be deduced, the ability to show that objects at two separated sites were formed at the same time requires additional information. A coin, vessel, or other common artifact could link two archaeological sites, but the possibility of recycling would have to be considered.
The World’s Oldest Ice
Dating by annual layer counting An ice sheet consists of layers strata of snow and ice, almost like a giant sandwich. In the inner part of the ice sheet where more snow accumulates than melts and evaporates the so-called accumulation zone , a new layer of snow is deposited on top of the previous layer of snow every year. The buried snow layers get compressed as more snow falls on top read more about the transformation of snow to ice here.
The layers are slowly transformed into ice and they are becoming thinner and older as they move downwards through the ice sheet and eventually melt or break off as icebergs at the ice sheet’s margins.
To help us understand what happened during the Ice Age, Peter Ward takes us on a tour of other mass extinctions through earth’s history. He presents a compelling account of the great comet crash that killed off the dinosaurs, and describes other extinctions that were even more extensive.
Donau There are four named major glaciations in North America. The earliest, the Nebraskan , is found on the plains of the central United States. The Kansan overlies it and extends slightly farther southwest into Kansas. The Illinoian , as the name implies, terminates primarily in Illinois. This last advance removed most evidence of earlier glaciations in these regions. The actual positions of the southern edges of these ice sheets varied considerably from glacial to glacial.
The northern extent of the ice is poorly known at best. Similar sequences are found from Scandinavian ice sheets and from ice in the Swiss and Austrian Alps. Glacial remnants Landforms There have certainly been previous periods of geologic time in which glaciers were extensive during the late Precambrian and the Permian Period , for example , but the Quaternary has left a distinctive imprint on modern landscapes and surface environments.
The most distinguishing characteristics of the Quaternary in middle and high latitudes are glacial sediments and evidence of glacial erosion. Glacial erosion is the predominant feature of high mountains such as the Alps , Himalayas , Andes , and Rockies. Glacial erosion has sculpted deep alpine valleys, and it has left sharp erosional remnants such as the Matterhorn in Europe.