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 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.
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 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.
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.
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 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.
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.
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.
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.
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.
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.
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.
Soot absorbs incoming solar radiation and can speed
glacial melting when
deposited on snow
in sufficient quantities.
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.
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).
An ice drilling pioneer, Oeschger was now measuring oxygen isotopes
in glacial - era lake
deposits near his home
in Bern, Switzerland.
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.
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.
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.