ESA: Mars’s mysterious elongated crater

[bystander]

Mars’s mysterious elongated crater
European Space Agency | Space Science | 27 Aug 2010

Orcus Patera [i](Credits: ESA/DLR/FU Berlin (G. Neukum))[/i]

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Orcus Patera is an enigmatic elliptical depression near Mars’s equator, in the eastern hemisphere of the planet. Located between the volcanoes of Elysium Mons and Olympus Mons, its formation remains a mystery.

Often overlooked, this well-defined depression extends approximately 380 km by 140 km in a NNE–SSW direction. It has a rim that rises up to 1800 m above the surrounding plains, while the floor of the depression lies 400–600 m below the surroundings.

The term ‘patera’ is used for deep, complex or irregularly shaped volcanic craters such as the Hadriaca Patera and Tyrrhena Patera at the north-eastern margin of the Hellas impact basin. However, despite its name and the fact that it is positioned near volcanoes, the actual origin of Orcus Patera remains unclear.

Aside from volcanism, there are a number of other possible origins. Orcus Patera may be a large and originally round impact crater, subsequently deformed by compressional forces. Alternatively, it could have formed after the erosion of aligned impact craters. However, the most likely explanation is that it was made in an oblique impact, when a small body struck the surface at a very shallow angle, perhaps less than five degrees from the horizontal.

The existence of tectonic forces at Orcus Patera is evident from the presence of the numerous ‘graben’, rift-valley-like structures that cut across its rim. Up to 2.5 km wide, these graben are oriented roughly east–west and are only visible on the rim and the nearby surroundings.
...
However, the presence of graben and wrinkle-ridges has no bearing on the origin of Orcus Patera, as both can be found all over Mars. The true origin of Orcus Patera remains an enigma.

[rstevenson]

A very interesting crater/patera. And there's lots more images at the linked ESA site. ESA always does a good job with images.

Thanks for this one bystander! (Mars, you may have noticed, is my fave planet.)

Rob

[neufer]

[b][color=#FF0000]Orcinus orca[/color][/b]

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<<Orcinus orca is the only recognized species in the genus Orcinus, one of many animal species originally described by Linnaeus in 1758 in Systema Naturae. Konrad Gessner wrote the first scientific description of a killer whale in his "Fish book" of 1558, based on examination of a dead stranded animal in the Bay of Greifswald that had attracted a great deal of local interest.

The killer whale is one of 35 species in the oceanic dolphin family, which first appeared about 11 million years ago. The killer whale lineage probably branched off shortly thereafter. English-speaking scientists most often use the term killer whale, although the term orca is increasingly used. Killer whale advocates point out that it has a long heritage. Indeed, the genus name Orcinus means "of or belonging to the kingdom of the dead", or "belonging to Orcus.">>

• ___ Finnegans Wake: Page 494
  
  -- Orca Bellona! Heavencry at earthcall, etnat athos? Extinct
  your vulcanology for the lava of Moltens!
  -- It's you not me's in erupting, hecklar!
  -- Ophiuchus being visible above thorizon, muliercula
  occluded by Satarn's serpent ring system,the pisciolinnies Nova
  Ardonis and Prisca Parthenopea, are a bonnies feature in the
  northern sky. Ers, Mores and Merkery are surgents below the rim
  of the Zenith Part while Arctura, Anatolia, Hesper and Mesembria
  weep in their mansions over Noth, Haste, Soot and Waste.

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<<Orcus was a god of the underworld, punisher of broken oaths in Italic and Roman mythology. The origins of Orcus may have lain in Etruscan religion. Orcus was a name used by Roman writers to identify a Gaulish god of the underworld. The so-called Tomb of Orcus, an Etruscan site at Tarquinia, is a misnomer, resulting from its first discoverers mistaking as Orcus a hairy, bearded giant that was actually a figure of a Cyclops. Orcus was chiefly worshipped in rural areas; he had no official cult in the cities. He survived as a folk figure into the Middle Ages, and aspects of his worship were transmuted into the wild man festivals held in rural parts of Europe through modern times.

The Romans sometimes conflated Orcus with other gods such as Pluto, Hades, and Dis Pater, god of the land of the dead. The name "Orcus" seems to have been given to his evil and punishing side, as the god who tormented evildoers in the afterlife. Like the name Hades (or the Norse Hel, for that matter), "Orcus" could also mean the land of the dead. From Orcus' association with death and the underworld, his name came to be used for demons and other underworld monsters, particularly in Italian where orco refers to a kind of monster found in fairy-tales that feeds on human flesh. The French ogre and the Italian orco are exactly the same sort of creature. An early example of an orco appears in Ludovico Ariosto's Orlando Furioso, as a bestial, blind, tusk-faced monster inspired by the Cyclops of the Odyssey.

In an unpublished letter sent to Gene Wolfe, Tolkien made this comment:
"Orc I derived from Anglo-Saxon, a word meaning demon, usually supposed to be derived from
the Latin Orcus -- Hell. But I doubt this, though the matter is too involved to set out here.">>

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<<The Eiger ("Ogre") is the easternmost peak of a ridge-crest that extends across the Mönch ("Monk") to the Jungfrau ("Maiden") at 4,158 m. The name has been linked to the Greek term akros, meaning "sharp" or "pointed", but more commonly to the German eigen, meaning "characteristic". The north face was not climbed until 1938 by an Austrian-German expedition and is one of the six Great north faces of the Alps, towering over 1,800 m above the valley of Grindelwald. Since 1935, at least sixty-four climbers have died attempting the north face, earning it the German nickname, Mordwand, or "death wall". >>