Sentences with phrase «precambrain glacial deposits»

The Dry Valleys» most striking similarity to the Red Planet is in glacial deposits laid down by ice so cold that meltwater never reworks the surface features.

In his mind, the site snuggled too closely to glacial deposits from the last ice age that lay atop the sloping Martian-esque hills.

* Chinese glacial deposits show that three of the oldest and coldest ice ages in Earth's history date from 600 to 750 million years ago.

They consist of blocks of horizontally layered glacial deposits, often complete with the overlying forest floor.

Lead author Martin Kennedy at the University of California, Riverside, and colleagues collected limestone and dolomite rocks from Precambrain glacial deposits in northern Namibia, central Australia and the North American Cordillera.

The tools were found beneath glacial deposits laid down during a period 450,000 years ago when the region was blanketed in ice, so they must be older than this.

When NASA's Mars Global Surveyor observed further evidence for ancient glacial deposits on Mars after it arrived in 1997, the idea became less outlandish.

When he started inspecting nearby craters to work out the direction of the sunlight and shadows, however, he realized that those channels weren't channels at all; they were ridges of material and possible evidence for glacial deposits.

Moraine Creek is certainly an apt name; it has carved through an impressive cake of glacial deposits containing rocks of all origins and colors, ground together, mixed, and mashed by creeping glaciers.

Bugs in software are one thing, but it is undoubtable that our ice - caps are glacial deposits are shrinking, and that the oceans are getting warmer.

Global warming, global cooling, glacial advances, glacial retreats, warm tropical seas, glacial deposits, etc, etc..

Examples of this type of data include tree ring width and density measurements, fossilized plant remains, insect and pollen frequencies in sediments, moraines and other glacial deposits, marine organism fossils, and the isotope ratios of various elements.

There are a number of different types of proxy data types in this group including glacial deposits, glacial erosional features, shoreline features, aeolian deposits, lake sediments, relict soil deposits, and speleothems (depositional features like stalactites and stalagmites).

One author, speculating about the coming of a new ice age, pointed to «evidence of (at least) five rapid hemispheric coolings of about 5 °C... each event spread over not more than about a century,» Flohn (1974), quote p. 385; one line of evidence was carbon - 14 studies of tree stumps in glacial deposits: Denton and Karlén (1973).

The peat layer is embedded in a sandy deposit capped by a glacial deposit.

Sohl, L.E., N. Christie - Blick, and D.V. Kent, 1999: Paleomagnetic polarity reversals in Marinoan (ca. 600 Ma) glacial deposits of Australia: Implications for the duration of low - latitude glaciation in Neoproterozoic time.

The continental glaciations of the Pleistocene left signatures on the landscape in the form of glacial deposits and landforms; however, the best knowledge of the magnitude and timing of the various glacial and interglacial periods comes from oxygen isotope records in ocean sediments.

The drill core penetrated 514 m of silts and silty clays (glacial deposits) punctuated by muds and episodic 0.02 — 1.2 m thick terrigenous sands (interglacial deposits) 22.

Not exact matches

Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glacial cycles.

In fact, the Libyan Sahara Desert contains unmistakable glacial scars and Antarctica has extensive coal deposits — and very likely abundant oil and gas — that establish that their plates were once at the other ends of the earth (see image at right).

The movement of these large masses of ice also leaves distinct marks on the walls of valleys and in the form of deposits of glacial sediment.

Bartek, L.R., and Anderson, J.B., 1991, Facies distribution resulting from sedimentation under polar interglacial climatic conditions within a high - latitude marginal basin, McMurdo Sound, Antarctica: in J.B. Anderson and G.M. Ashley, eds., Paleoclimatic Interpretation of Glacial Marine Deposits, Special Publication 261, Geological Society of America, Boulder, p. 27 - 49.

Here we show that the East Greenland Ice Sheet existed over the past 7.5 million years, as indicated by beryllium and aluminum isotopes (10Be and 26Al) in quartz sand removed by deep, ongoing glacial erosion on land and deposited offshore in the marine sedimentary record.

This is because terrestrial deposits of ancient glacial and interglacial periods1 — 3 are overrun and eroded by more recent glacial advances, and are therefore usually rare, isolated and poorly dated.

The concentrations were lowest in the eastern and far western states where the soil had been tilled the longest, and were highest in Deaf Smith County, Texas, where excavations proved the roots of the wheat grass to pass down six feet or more through three feet of top soil into deposits of glacial pebbles cemented together with calcium carbonate.

As the oceans levels rose, glacial waters flowed through the limestone deposits of the then exposed Lighthouse Reef resulting in huge subterranean caverns.

A group of related photographs documents the enormous glacial erratics that were deposited around Pelham Bay.

It turns out that the overlying fresh water aquifer in the glacial till (deposited during the last glacial max) helps maintain an enormous biogenic nursery within the underlying Antrim (the anaerobic microbes need fresh water).

Sand deposits can be found in glacial outwash plains.

You should ask your Tardlie friend what kind of soil he expects to find in the north given that virtually all of it was scraped off and deposited north of the 49th during the last glacial period.

I've sometimes thought that global cataclysms like the largest volcanic eruptions would disrupt the glacial records by many years, like Oruanui eruption c. 26500bp, as these would induce unrecorded behavior in weather and other things, f.e. the huge ash deposits might decrease the albedo so much a local melting event happens.

Major ice sheets, in particular in Greenland [8], ocean methane clathrate deposits [9], and future evolution of glacial / interglacial cycles [10] might be affected by that long tail.

Soot absorbs incoming solar radiation and can speed glacial melting when deposited on snow in sufficient quantities.

Yellowstone's northern range of sagebrush - grasslands and bison, elk, wolf, and bear inhabitants is founded on glacial moraines, sub-glacial till, and outwash deposited during the last glaciation.

Regarding Bangladesh, there was something in the press about a year ago that said Bangladesh is actually ADDING land area, because so much dirt / glacial silt is washed down the huge rivers, and is deposited in the deltas, so that even with sea level rise, more land is created.

An ice drilling pioneer, Oeschger was now measuring oxygen isotopes in glacial - era lake deposits near his home in Bern, Switzerland.

We can determine the past climate of the Earth by mapping the distribution of ancient coals, desert deposits, tropical soils, salt deposits, glacial material, as well as the distribution of plants and animals that are sensitive to climate, such as alligators, palm trees & mangrove swamps.

Despite slow rates of plant growth in the Arctic and sub-Arctic latitudes, massive deposits of peat have accumulated there since the last glacial maximum (Smith et al., 2004; MacDonald et al., 2006).

Imputities are a main problem in Greenland ice cores where a mix of seasalt / carbonate and acidic dust from Icelandic volcanoes can produce CO2 in situ, but is less of interest in deep inland Antarctic ice cores, except during the deepest times of glacials, when far more dust is deposited.

above: the calling - card of an ancient ice - age - an outcrop in Namibia of an ancient (Proterozoic) tillite of glacial origin, overlain by a dolomitic «cap - carbonate» sequence of marine origin, deposited in warmer post-glacial conditions.