According to University of Washington geologist and tsunami expert Jody Bourgeois, the idea that chevrons – a type of large U- or V-shaped formations found along certain coasts – were caused by mega-tsunamis is pure nonsense.
The term chevron refers a special type of vast dunes shaped a bit like the stripes on soldier’s uniform. They can be anything from hundreds of meters to a kilometre in length and can be seen in places such as Egypt, the Bahamas, Madagascar, and Australia.
Some scientists have suggested that a possible explanation for these mysterious stripes is mega-tsunamis caused by asteroid or comet impact. According to this school of thought, the chevrons may be deposits left by gigantic tsunamis 4,800 to 5,000 years ago, tsunamis that might have been up to 10 times larger than the earthquake-caused Indian Ocean tsunami of December 2005. Due to the location of known chevrons, the Indian Ocean has been suggested as ground zero for the comet or asteroid impact.
Bourgeois, a professor of Earth and space sciences who has studied earthquakes and tsunamis in various parts of the world, does not agree. According her, the chevrons are not lined up the way you would expect from deposits caused by gigantic waves. Many of the chevrons on Madagascar are for instance parallel to the coastline, instead of perpendicular to the shore.
Models created by Bourgeois’ colleague Robert Weiss, assistant professor of geology at
Texas A&M University, show that deposits formed by gigantic tsunamis would point in the same direction as the waves were travelling when the reached land, which is mostly perpendicular to the shore.
“And if it really was from an impact, you should find evidence on the coast of Africa too, since it is so near,” Bourgeois explains.
The computer model generated actual conditions for a tsunami which made it possible to use the model to explore the effects of an asteroid or comet hitting the part of the Indian Ocean suggested by mega-tsunami chevron proponents. According to the model, the gigantic waves would approach land at a 90-degree orientation to the chevron deposits.
“The model shows such a tsunami could not have created these chevrons, unless you have some unimaginable process at work,” Bourgeois says.
Bourgeois and Weiss have used satellite images from Google Earth to get close-up looks at chevrons in different locations. Chevron are most common in coastal regions but you can find quite a lot of them in semiarid inland areas as well.
Bourgeois and Weiss wrap up their paper, which can be found in the May issue of the journal Geology, by stating that “the extraordinary claim of ‘chevron’ genesis by megatsunamis cannot withstand simple but rigorous testing. […] There are the same forms in the Palouse in eastern Washington state, and those are clearly not from a tsunami.”
Remember the strange fish discovered by divers off the Indonesian coast in January 2008? This fish has now been scientifically described and given the official name Histiophryne psychedelica. Well, what else would you call a fish that that looks like this and moves like it was permanently and irrevocably under the influence?
Histiophryne psychedelica, also known as the Psychedelic frogfish, was scientifically described by Ted Pietsch[1] and Rachel Arnold[2] of the University of Washington, together with wildlife photographer David Hall[3].
The University of Washington has released videos where you can see the Psychedelic frogfish swim, or rather hop, skip and jump, over a coral reef. http://uwnews.org/article.asp?articleID=47496
Each time the fish strikes the reef, it uses its fins to push off while simultaneously expelling water from tiny gill openings on the sides of the body to aid in propulsion. The fish is well suited for life on the reef and has for instance been blessed with protective thick folds of skin that keeps its gelatinous body out of harms way among the sharp-edged corals. Just as on the other members of the frogfish group, the fins on both sides of the body have evolved into elongated protrusions more similar to legs than fins. Histiophryne psychedelica does however distinguish itself from other frogfish species by having a flat face with eyes facing forward.
Frogfishes are a type of angelfish, but unlike most other anglers Histiophryne psychedelica does not have any lures on its forehead to tempt its prey with. It also seems to keep its vibrant colours in all sorts of environments, unlike most other anglers who prefer to adapt every inch of their body (except for the lures) to the surroundings in order to stay undetected by prey. According to Hall, the psychedelic colouration might be a way for the fish to mimic corals.
When a Psychedelic frogfish is killed and preserved in ethanol, it looses its lively colours and patterns within a few days and takes on a dull white appearance. This made Pietsch curious about two specimens sent to him in 1992 and he decided to take a closer look at them in a microscope. In the newly caught specimen, the distinctive striping of the fish could still be seen through a microscope and this prompted Pietsch to re-examine the two preserved ones in search of patterns. As it turned out, these two fishes had the same characteristic striping as Histiophryne psychedelica – Pietsch had been storing two specimens of the psychedelic fish for 17 years without realizing it.
If you wish to learn more about this mesmerizing fish, check out the paper Theodore W Pietsch, Rachel J. Arnold and David J. Hall. “A Bizarre New Species of Frogfish of the Genus Histiophryne (Lophiiformes: Antennariidae) from Ambon and Bali, Indonesia.” Copeia[4], February 2009. The study was funded by the National Science Foundation.
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Lophiiformes
Family: Antennariidae
Genus: Histiophryne
New species: Histiophryne psychedelica
[1] Dr Ted Pietsch, University of Washington (UW) professor of aquatic and fishery sciences and curator of fishes at the UW Burke Museum of Natural History and Culture
[2] Rachel Arnold, University of Washington master’s student in aquatic and fishery sciences
[3] David Hall, wildlife photographer and owner of Seaphotos.com
[4] Copeia, the official publication of the American Society of Ichthyologists and Herpetologists, can be found on www.asih.org.