Sentences with phrase «sea sediments which»

Permafrost was known to contain gas hydrates — icelike mixtures of water and organic gases first identified in deep - sea sediments which form only at very high pressures and low temperatures.

Not exact matches

Inadequate flood protection infrastructure, which right now might not contain high tides in El Nino years; Lack of action on annual sediment removal from spring freshets, which each year move over 30 million m3 of sediment and leave about 3 million m3 of silt in the navigation and secondary channels of the lower reaches; and, By the end of this century sea levels at the mouth of the river could potentially rise more than one meter due to climate change overtopping the diking system.

This age was based on isotopic dating of 5 meteorites and a representative sample of modern Earth lead from a Pacific deep - sea sediment, all of which plot along a linear isochron on a graph of 207Pb / 204Pb versus 206Pb / 204Pb (Patterson, 1956).

That fits with analysis of sea - floor sediments, which suggests that a dead zone of around 600 square kilometres formed here about 40,000 years ago.

They note that it is completely buried by sediments from more recent eras, which indicates it was formed long before its surroundings, and that it has no topographic expression on the present sea floor.

The charring helped preserve plant remains at the site, which was then buried by sediment and inundated as the sea expanded.

This creates a vacuum in the sediment, which draws fresh sea water into the marine aquifer.

The key to finding the oldest wrecks, he says, is locating «relic surfaces» that have escaped being buried by sediment, which flows downhill and covers the deep sea floor.

By dating the various sediment layers, researchers realised that the mass extinction of the Permian - Triassic boundary is represented by a gap in sedimentation, which corresponds to a period when the sea - water level decreased.

Most of our sea - level records are based on the chemical make - up of sediment cores, which are hard to date — estimates can be thousands of years out.

This research evolved into the Deep Sea Drilling Project, which has sampled sea - floor sediment around the gloSea Drilling Project, which has sampled sea - floor sediment around the glosea - floor sediment around the globe.

Microorganisms living in basaltic sea floor buried beneath sediments derive energy from inorganic components from the host rocks that interact with infiltrating seawater, which brings dissolved oxygen and other trace nutrients with it.

The purpose was to create a bathymetric picture of the sea bottom and to collect reflection seismic data, which allows researchers to peer into the sediments and rocks underneath the seafloor.

But the St. Elias range also contains some of the world's largest glaciers, which inexhaustibly scour the mountains and dump sediment in the sea.

In 1991, the IMO adopted guidelines which recommend that ships should avoid taking on ballast in shallow areas and during toxic blooms of marine algae; keep accurate records of where and when ballast is loaded; exchange ballast water at sea, where toxic organisms are rare; and discharge sediments into approved areas at the port of destination («End of the line for deadly stowaways», New Scientist, 24 October 1992).

Surprise find The team's actual mission was to survey ocean currents near the Ross Ice Shelf, a slab of ice extending more than 600 miles (970 kilometers) northward from the grounding zone of the West Antarctic Ice Sheet into the Ross Sea, to model the behavior of a drill string, a length of pipe extending to the seafloor which delivers drilling fluids and retrieves sediment samples.

Instead, the law directs the agency to run 10 pilot projects across the country in which dredged sediment will be used to restore and protect coastlines instead of being dumped as waste, often at sea.

The ice formation and offshore winds produce strong currents in these shallow marginal seas, which stir up the sediment and carry the methane produced there into the water column.

The researchers, which include U.S. teams from NOAA, the U.S. Geological Survey (USGS), and the University of New Hampshire, will be collecting seismic data from this region by bouncing sound blasts off the sea floor to determine its sediment makeup, as well conducting a multibeam analysis that will give them an idea of the shape of the ridge.

On a hypothetical journey to the centre of the Earth starting at the sea floor, you would travel through sediment, a layer of basalt, and then hit the gabbroic layer, which lies directly above the mantle.

However, many of the sources along the continental slope lie at cold depths in which ices have formed at high pressures within sea - floor sediments, which once trapped methane produced by microbes living there.

There, they collected mud from the sea floor, which builds up for millions of years like a giant layer cake as newer sediments pile on top of older ones.

This is, in part, a function of their low elevations, which rarely exceed 3 m above mean sea level, as well as their often poorly consolidated sediment - dominated structures.

Even if you ignore all the temperature meauserments which you seem to vehimently deny there is still many other sources of evidence associated with this increase such as — ice melt / extreme weather events / sea current changes / habitat changes / CO2 / ice cores / sediment cores.

This chemical weathering process is too slow to damp out shorter - term fluctuations, and there are some complexities — glaciation can enhance the mechanical erosion that provides surface area for chemical weathering (some of which may be realized after a time delay — ie when the subsequent warming occurs — dramatically snow in a Snowball Earth scenario, where the frigid conditions essentially shut down all chemical weathering, allowing CO2 to build up to the point where it thaws the equatorial region, at which point runaway albedo feedback drives the Earth into a carbonic acid sauna, which ends via rapid carbonate rock formation), while lower sea level may increase the oxidation of organic C in sediments but also provide more land surface for erosion... etc..

«The rate at which sediment is deposited and new land is created is much slower than the rate at which climate change and sea level rises are taking place,» he said.

>... there are still ways of discovering the temperatures of past centuries,... tree rings... Core samples from drilling in ice fields... historical reconstruction... coral growth, isotope data from sea floor sediment, and insects, all of which point to a very warm climate in medieval times.

Each time they go there's more and more bubbles coming out, and the fear is that there'll be a general release of methane trapped under those sediments, which could cause a very rapid rise in the rate of sea level.

This has never happened before because the sea ice never retreated very much in the summer and the water temperature could not rise above zero because of the ice cover... The permafrost is acting as a cap for a very large amount of methane (CH4), which is sitting in the sediments underneath in the form of methane hydrates.

''... worked with two sediment cores they extracted from the seabed of the eastern Norwegian Sea, developing a 1000 - year proxy temperature record «based on measurements of δ18O in Neogloboquadrina pachyderma, a planktonic foraminifer that calcifies at relatively shallow depths within the Atlantic waters of the eastern Norwegian Sea during late summer,» which they compared with the temporal histories of various proxies of concomitant solar activity... This work revealed, as the seven scientists describe it, that «the lowest isotope values (highest temperatures) of the last millennium are seen ~ 1100 - 1300 A.D., during the Medieval Climate Anomaly, and again after ~ 1950 A.D.» In between these two warm intervals, of course, were the colder temperatures of the Little Ice Age, when oscillatory thermal minima occurred at the times of the Dalton, Maunder, Sporer and Wolf solar minima, such that the δ18O proxy record of near - surface water temperature was found to be «robustly and near - synchronously correlated with various proxies of solar variability spanning the last millennium,» with decade - to century - scale temperature variability of 1 to 2 °C magnitude.»

On still longer time scales, acidification by the invading CO2 dissolves carbonate sediments on the sea floor, which further enhances ocean uptake.

Sea level from equations (3.3) and (3.4) is shown by the blue curves in figure 2, including comparison (figure 2c) with the Late Pleistocene sea - level record of Rohling et al. [47], which is based on analysis of Red Sea sediments, and comparison (figure 2b) with the sea - level chronology of de Boer et al. [46], which is based on ice sheet modelling with the δ18O data of Zachos et al. [4] as a principal input driving the ice sheet modSea level from equations (3.3) and (3.4) is shown by the blue curves in figure 2, including comparison (figure 2c) with the Late Pleistocene sea - level record of Rohling et al. [47], which is based on analysis of Red Sea sediments, and comparison (figure 2b) with the sea - level chronology of de Boer et al. [46], which is based on ice sheet modelling with the δ18O data of Zachos et al. [4] as a principal input driving the ice sheet modsea - level record of Rohling et al. [47], which is based on analysis of Red Sea sediments, and comparison (figure 2b) with the sea - level chronology of de Boer et al. [46], which is based on ice sheet modelling with the δ18O data of Zachos et al. [4] as a principal input driving the ice sheet modSea sediments, and comparison (figure 2b) with the sea - level chronology of de Boer et al. [46], which is based on ice sheet modelling with the δ18O data of Zachos et al. [4] as a principal input driving the ice sheet modsea - level chronology of de Boer et al. [46], which is based on ice sheet modelling with the δ18O data of Zachos et al. [4] as a principal input driving the ice sheet model.

That makes me wonder, is there a critical rate of sea level rise above which the reefs can't collect sediment quickly enough to keep up?

«The rate at which sediments is deposited and new land is created is much slower than the rate at which climate change and sea level rises are taking place.»

They found that the dense, salty water from the Marmara Sea — which leads out to the Aegean and Mediterranean Seas at the other end of the Bosphorus — is flowing out of the strait and along the bottom of the Black Sea, carrying along sediment and nutrients that could be key in providing vital nutrients to remote parts of the ocean.

Besides the information about greenhouse - gas levels from the trapped air bubbles at Vostok, a sediment core from the bottom of the Red Sea indicates changes in sea level, which in turn give an approximation of ice sheet arSea indicates changes in sea level, which in turn give an approximation of ice sheet arsea level, which in turn give an approximation of ice sheet area.