Weird Swirly Things

[neufer]

[b][color=#0000FF]Cooling lava on Mars can form patterns like snail shells when the lava is pulled in two directions at once. Such patterns, rare on Earth, have never before been seen on Mars. This image, with more than a dozen lava coils visible, shows an area in a volcanic region named Cerberus Palus that is about 500 meters wide.[/color][/b]

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[b][color=#0000FF]A small lava coil on pahoehoe flow, Kilauea Volcano, Hawai`i (see the [/color][color=#FF0000]pocket knife[/color][color=#0000FF] for scale.) Credit: W.W. Chadwick[/color][/b]

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Weird Swirly Features Found on Mars
by Nancy Atkinson, Universe Today, April 26, 2012

<<Strange coiling spiral patterns have been found on Mars surface by a graduate student who was doing what many of us enjoy: looking through the high-resolution images from the HiRISE camera on the Mars Reconnaissance Orbiter. Similar features have been seen on Earth, but this is the first time they have been identified on Mars. However, on Mars, these features, called lava coils, are supersized. “On Mars the largest lava coil is 30 meters across – that’s 100 feet,” said Andrew Ryan from Arizona State University. “That’s bigger than any known lava coils on Earth.”

The lava coils resemble snail or nautilus shells. Ryan has found about 269 of these lava coils just in one region on Mars, Cerberus Palus. 174 of them swirl in a clockwise-in orientation, 43 are counterclockwise, and 52 of the features remain unclassified due to resolution limits.

On Earth, lava coils can be found on the Big Island of Hawaii, mainly on the surface of ropey pahoehoe lava flows. They usually form along slow-moving shear zones in a flow; for example, along the margins of a small channel, and the direction of the flow can be determined from a lava coil.

“The coils form on flows where there’s a shear stress – where flows move past each other at different speeds or in different directions,” said Ryan. “Pieces of rubbery and plastic lava crust can either be peeled away and physically coiled up – or wrinkles in the lava’s thin crust can be twisted around.”

Similarly, Ryan said scientists have documented the formation of rotated pieces of oceanic crust at mid-ocean ridge spreading centers. But Ryan and the co-author on the paper, Phil Christiansen, Principal Investigator for the Thermal Emission Imaging Spectrometer on the Mars Odyssey spacecraft, are certain water has nothing to do with the formation of the lava coils on Mars.

“There are no known mechanisms to naturally produce spiral patterns in ice-rich environments on the scale and frequency observed in this area,” they wrote in their paper. “It is also unlikely that ice-rich patterned regolith, which takes decades to centuries to develop, could fracture and drift. The lava coils and drifting polygonal and platy-ridge lava crust described above are therefore most consistent with known volcanic analogs, rather than ice-related processes.”

These features are probably quite young, formed 1.5 to 200 million years ago in Mars’ late Amazonian period
when the planet was volcanically active. >>

[bystander]

ASU grad student discovers new form of lava flow on Mars
Arizona State University | 2012 Apr 26

Swirly lava patterns in beautiful HiRISE images
Planetary Society | Emily Lakdawalla | 2012 Apr 26

[geckzilla]

Needs a nice big image and then made into an apod.

[bystander]

Needs a nice big image and then made into an apod.

Cooling lava on Mars can form patterns like snail shells when the lava is pulled in two directions at once. Such patterns, rare on Earth, have never before been seen on Mars. This image, with more than a dozen lava coils visible, shows an area in a volcanic region named Cerberus Palus that is about 500 meters (1640 feet) wide.

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[geckzilla]

Yeah!! I have quite a fondness for swirls.

[neufer]

Yeah!! I have quite a fondness for swirls.

• All dimpled cheeks and curls,
  Your head it simply swirls.
  Those girls, those girls,
  Those lovely seaside girls.

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<<The Martians are described as octopus-like creatures; the "body" consists of a disembodied head about four feet across, having two eyes; a beak-like mouth; and two branches of eight 'almost-whip like' tentacles each around the mouth, which have been nicknamed the 'hands'. They reproduce asexually, children being born by "budding" off a parent. Internally, the Martians consist of a brain, lungs, heart, and blood vessels; they have no organs for digestion, and therefore sustain themselves by mechanically transfusing blood from other animals into their arteries by means of pipettes. The ear, a single membrane located in the back of the head, is believed to be useless in Earth's atmosphere. Their arrival on Earth is by means of cylindrical capsules launched by a cannon from Mars, and their chief weapon of war is the Martian 'Heat-Ray', which produces a white flame consuming any organism it touches. This is mounted on long poles sometimes attached to a "monstrous tripod", later titled the fighting-machine, which travels across the landscape destroying cities.>>

[b][color=#0000FF]Parapuzosia seppenradensis[/color][/b]

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<<Ammonites are an extinct group of marine invertebrate animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs are more closely related to living coleoids (i.e. octopuses, squid, and cuttlefish) than they are to shelled nautiloids such as the living Nautilus species. Ammonites are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods. Their fossil shells usually take the form of planispirals, although there were some helically-spiraled and non-spiraled forms (known as heteromorphs).

Parapuzosia seppenradensis is the largest known species of ammonite. It lived during the Late Cretaceous period. A specimen found in Germany in 1895 measures 1.95 m in diameter, although the living chamber is incomplete. It is estimated that if complete, this specimen would have had a diameter of approximately 2.55 m.

The name ammonite, from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams' horns. Pliny the Elder (d. 79 AD. near Pompeii) called fossils of these animals ammonis cornua ("horns of Ammon") because the Egyptian god Ammon (Amun) was typically depicted wearing ram's horns. Often the name of an ammonite genus ends in -ceras, which is Greek (κέρας) for "horn".>>

[bystander]

Mars coils hold with those who favour fire
New Scientist | Astrophile | Lisa Grossman | 2012 Apr 27

Object: Spiral patterns in Martian valleys
Origin: Solidified lava lake

[i]Spirals in Mars's valley could only be formed by volcanic processes (Image: NASA/JPL-Caltech/Arizona State University)[/i]

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• Fire and Ice
  by Robert Frost
  
  Some say the world will end in fire,
  Some say in ice.
  From what I've tasted of desire
  I hold with those who favor fire.
  But if it had to perish twice,
  I think I know enough of hate
  To say that for destruction ice
  Is also great
  And would suffice

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Some say Mars's northern valley formed in fire, some say in ice: now curious spirals on the floor of the valley have been glimpsed – and hold with those who favour fire.

The Athabasca Valles region, a channelled and scabbed valley just north of the red planet's equator, was clearly carved by floods of fluid coursing through it tens of millions of years ago. But, in a beautiful echo of the apocalyptic poem "Fire and Ice" by American poet Robert Frost, no one had been able to work out whether that fluid was water or molten lava.

Graduate student Andrew Ryan of Arizona State University and colleagues seem to have settled the debate with their discovery of subtle spirals on the valley floor that could only be formed from lava. "These coils can only be formed by volcanic processes," says Ryan.

Athabasca Valles is famous for its large dark plates, which seem to be floating in a network of channels that were probably carved in a flood of liquid water. The plates look a lot like the broken floes of pack ice found in the Arctic Ocean on Earth. The land between them is criss-crossed by a network of polygons that look like frozen glacial terrain found on Earth and near Mars's poles.

Ocean of consternation

In 2005, Bruce Murray of the California Institute of Technology in Pasadena and colleagues suggested that those features mean there's a large frozen ocean in Athabasca Valles.

"That caused a lot of consternation," Ryan says. The Phoenix Lander found ice below the Martian surface near the north pole, but Athabasca Valles is just 4 or 5 degrees north of the equator. "We don't expect ice to be present so close to the equator on Mars."

Cooling lava could form the same features. As the surface of a slow-moving lava flow cools, a thin skin forms on top of the hot viscous liquid. That crust can break apart and drift, forming the large plates. The crust also contracts as it cools, which makes it break into polygons. Similar features show up on the Big Island of Hawaii on Earth.

Unfortunately, there was no way to choose between the fiery or icy version of events.

Wrinkled skin

In October, Ryan was examining images from the sharp-eyed HiRISE camera on NASA's Mars Reconnaissance Orbiter, which can resolve objects the size of a beach ball from nearly 300 kilometres away.

He noticed strange snail-like spiral patterns ranging between 5 and 30 metres in diameter on Cerberus Palus, a plain southwest of Athabasca. "The first time I saw them, all I could think was 'Holy crap! What am I looking at here?'" he says. "I was blown away. I was completely surprised."

The spirals could have formed on top of a cooling lava lake that pooled in the region after flowing from fissures to the northeast down the previously formed channels of Athabasca. Wrinkles in the rubbery skin that solidified on top of the lake could have twisted and become frozen in the coils.

They could also have formed when two flows of lava travelling in different directions or at different speeds moved past each other, creating turbulence that curled the lava into spirally whorls. The same effect sometimes happens in clouds or in bands of gas on Saturn and Jupiter.
Unique coils?

Similar spirals have been seen at mid-ocean ridges, where material wells up from the Earth's mantle and rotates pieces of oceanic crust. The same thing could have happened in a lava lake where two solid plates were spreading apart, Ryan says.

Ryan and his graduate advisor Philip Christensen found 296 spirals in a single HiRISE image that covered 90 square kilometres. Strangely, they've only seen two spirals in other images, and those were not as well preserved.

"We're not sure if the lava coils are found elsewhere on Mars," he says. "Are they pervasive elsewhere, or is this literally the only spot where they occurred? Either way will raise some interesting questions."

If he were still alive, what might the poet Robert Frost have taken from the discovery? It might have been comfort, or disappointment, that a planet strangely like Earth formed in the fires of desire, rather than icy hate.

Coils and Polygonal Crust in the Athabasca Valles Region, Mars, as Evidence for a Volcanic History - Andrew J. Ryan, Philip R. Christensen

• Science 336(6080) 449 (27 Apr 2012) DOI: 10.1126/science.1219437

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