Author: Marci

I am a senior geology major/biology minor at Dickinson College, in Carlisle, Pennsylvania.

Sinking down to the summit

By Marci Wills, May 2, 2010

Scientists like to categorize life on Earth into “biomes”. This is just a fancy name for regions characterized by similar biological and physical characteristics. For example, rain forests, temperate forests, savannas and deserts are some of the most well known and explored biomes. Little is known however, about many biomes of the oceans. Just last week, scientists from NOAA and Texas A&M- Corpus Christi revealed data suggesting that oceanic seamounts comprise one of the most widespread and diverse biomes on Earth.

Seamounts are underwater mountains which rise from the ocean floor but do not break the water’s surface. Most often they are extinct volcanoes, as in the emperor seamounts which are an extension of the Hawaiian Islands. Previous perception has been that seamounts were isolated and remote, but this idea is gradually changing. In their paper published last week in Oceanography, Peter Etnoyer, John Wood and Thomas Shirley claim that seamounts cover a substantial portion of the Earth, an area collectively larger than Australia.

Global distribution of 11,880 seamounts rising over 1000m above the seafloor

Their study used “satellite altimetry”, where specially-equipped satellites use radar beams to measure the elevation of the earth and sea level to within a few cm of accuracy. The use of satellite altimetry on the deep ocean floor is less precise, so the researchers looked for the most prominent seamounts rising at least 1000 meters. They counted about 11,880 of these worldwide, covering a cumulative area of 9,938,000 square kilometers, and that is their conservative estimate. That would make seamounts one of the most prevalent biomes in the world, ranking about even with the global extent of tropical humid forests, temperate broadleaf forests and wetlands.

Although organisms living on many seamounts never see sunlight, are surrounded by cold temperatures and high salinity water, and must rely on material falling from the surface waters for food, these elevated regions are undersea islands of biodiversity, sustaining much more life than surrounding seafloor. Only 200 seamounts have been thoroughly explored, but new species have been observed on nearly every submarine dive. In the Gulf of Alaska, two dozen new species of corals and sponges have been collected from seamounts since 2002.

This study demonstrates that rather than isolated features, seamounts often occur in dense clusters which vary significantly in size and number. The densest aggregation of seamounts is in the center of the Pacific Ocean where they are concentrated in a region exceeding the area of China. According to Project leader Peter Etnoyer, “Unlike beaches or coral reefs, most people will never see a seamount, but this study shows that they are clearly one of the predominant ecosystems on the planet”.

Sources:

Entnoyer, P.J., Wood, J., and Shirley, T.C., 2010, How large is the seamount biome?: Oceanography, v. 23, p. 206-209.

http://www.eurekalert.org/pub_releases/2010-04/nh-sis042910.php

Icelandic volcanoes spew Hydrofluoric acid… just one more reason why living on Earth is sometimes difficult.

By Marci Wills, April 18th, 2010

It seems that Earth is especially determined to show off its tricks this year. The ongoing eruption of Eyjafjallajokull (how do you pronounce that?) volcano in Iceland this week serves as yet another powerful reminder that we must organize our lives around the unpredictable workings of our planet. The continued cessation of air travel across Europe due to Eyjafjallajokull’s ash cloud is more than a slight inconvenience, but the research of Hildur Gestsdottir of the Institute of Archaeology in Rejkjavik suggests that the eruption may pose an even more severe threat. She believes that hydrofluoric acid emmitted from the Icelandic volcanoes has killed hundreds, if not thousands, of Europeans in previous severe eruptions.

Aerial view of the ash cloud over Eyjafjallajokull last Thursday

Iceland’s most devastating eruption of historic time was that of the offshore volcanic peak, Laki, in 1783. Laki spewed ash into the air over 8 full months and 10,000 Icelanders (roughly 1 in 5) died. Laki’s ash cloud altered European weather patterns, resulting in consecutively one of Europe’s hottest summers followed by its  most severe winter on record in 1873, both of which were associated with higher than normal death rates in Europe that year. Still, Hildur Gestsdottir believed that there were other reasons behind why the death toll in Iceland was so high. Survivors of the Laki eruption noted that their sheep and other livestock developed knobby protrusions from their bones, a telltale sign of fluorosis, or fluoride poisoning, just before dying. When Hildur excavated late 18th century graves in 2004, she found that many of those buried just after the eruption showed similarly abnormal bone growths. Hildur believes that these people were drinking water with concentrations of 30 to 40 ppm of hydrofluoric acid, enough to make you feel sick, but the poisoned ash was so pervasive that they simply had no other option.

The current Eyjafjallajokull eruption is not expected to reach a Laki-like scale. The ash cloud is located at ~30,000 ft, unfortunately the same altitude at which planes fly, but luckily below the stratosphere where volcanic gases can have a global effect because of a lack of rain there. Atmospheric scientist Brian Toon of the University of Colorado Boulder expects that the ash cloud from Eyjafjallajokull will be washed away by rain as it drifts further to the east. Still, hydrofluoric acid may become a worry if the eruption continues much longer. Fluoride-rich volcanic ash clings to vegetation and may affect crops and livestock even at low concentrations. If continuously ingested at high concentrations, people and animals can begin to die within several months. The effects of fluoride-rich volcanic ash are not fully understood as such Fluoride-rich lava is characteristic only of the volcanoes in Iceland and some in Melanesia.

Iceland has about 130 volcanoes, 18 of which have erupted since the settlement of the island in 900 C.E. Events of the scale of the Laki disaster are expected to occur there every 500 to 1000 years. As part of learning to survive on our planet, it is important to consider the challenges of keeping food and drinking water fluoride-free (and free of other various volcanic poisons) in the midst of air traffic, and possibly communication, shutdown due to volcanic eruptions.

Sources:

http://www.eurekalert.org/pub_releases/2010-04/uoca-vei041510.php

http://www.nytimes.com/2010/04/16/world/europe/16iht-scene.html

Stone, R., 2004, Iceland’s Doomsday Scenario: Science, News Focus, v. 306, p. 1278-1281.

Happy New-Geologic-Epoch!

By Marci Wills, April 4, 2010

Get out your party hats, because we may soon be welcoming in a new geologic epoch! Some scientists believe that humanity has affected the Earth so drastically over the past two centuries that changes may be significant enough to mark a new age of geologic time. Last week, earth scientists Jan Zalaseiwicz, Mark Williams (University of Leicester, UK), Will Steffen (Australian National University, Canberra), and Paul Crutzen (Max-Planck-Institute for Chemistry, Mainz, Germany) formally made the case for the addition of the “Anthropocene Epoch” to the Geologic Time Scale in the American Chemical Society’s journal, Environmental Science and Technology. More importantly, they warn that the Anthropocene could be accompanied by Earth’s next great mass extinction.

Evidence for the Anthropocene appears irrefutable from space

The Geologic Time Scale partitions 4.57 billion years of Earth’s history into four eras which contain shorter periods (For example, the Mesozoic era includes the Triassic, Jurassic, Cretaceous periods) and even finer epochs. Currently we live in the Holocene epoch which began ~11,000 years ago with the end of the most recent ice age.

Transitions between major divisions on the time scale are marked by observable changes in the sedimentary record worldwide. Usually, these are associated with upheavals in the planet’s climate and biodiversity. In their paper last week, the four scientists argue that “The scale of change taken place so far, or that is imminent or unavoidable, appears to have already taken the Earth out of the envelope of conditions and properties that mark the Holocene Epoch”

In addition to widely recognized changes in atmospheric composition, global temperature rise, melting polar ice, and rising sea levels, the study argues that many other human-induced effects are plainly visible on the Planet. Humans have brought about an order of magnitude increase in worldwide erosion rates, and the Anthropocene can be recognized by a variety of human-made sediment layers; the concrete of our roads and cities, the soils of our fields, and the polluted muds of estuaries, to name a few.

Most importantly, these scientists suspect that the Anthropocene may coincide with the world’s 6th mass-extinction event. Already, current extinction rates are estimated to be 100 to 1000 times greater than the normal background level and another 10-fold increase is expected this century.

The geologic time scale is overseen by multiple governing bodies under the International Union of Geological Sciences, all which will have to be convinced before “The Anthropocene” is officially adopted. But according to these four researchers, “However these debates unfold, the Anthropocene represents a new phase in the history of both humankind and of the Earth, when natural forces and human forces become intertwined, so that the fate of one determines the fate of the other. Geologically, this is a remarkable episode in the history of the planet”

Sources:

Zalasiewicz, J., Williams, M., Steffen, W., Crutzen, P., 2010, The new world of the Anthropocene: Environmental Science and Technology, v. 44, p. 2228-2231.

http://www2.le.ac.uk/ebulletin/news/press-releases/2010-2019/2010/03/nparticle.2010-03-26.0882152385

Feb. 27th Chilean Earthquake no shock to geophysicists

By Marci Wills, March 6, 2010

A building damaged in Conception, Chile by the February 27th, 2010 earthquake

The enormous magnitude 8.7 earthquake which struck Chile last Saturday (February 27th) in startling proximity to the Haiti disaster has lead some of my friends and family to an apocalyptic level of speculation. They want to know what freak force of nature caused these earthquakes to occur so close together? But it is important to remember that earthquakes are a normal occurrence on Earth that can happen at any time. In fact, last week’s upheaval in Chile came as no surprise to the scientific community and to two geophysicists in particular who expected it to happen.

Jian Lin of the Woods Hole Oceanographic Institute (Woods Hole, MA) and Ross Stein of the United States Geological Survey (Menlo Park, CA), had anticipated an earthquake in the location of the Feb 27th event since the completion of their research in the region 6 years ago. In a paper published in the Journal of Geophysical Research in February of 2004, they warned that this area was at increased risk of a large earthquake due to after effects of the world’s largest recorded quake, a magnitude 9.5 event, which occurred in Chile in 1960.

Both the 1960 and 2010 Chilean earthquakes occurred just off the west coast of Chile along a tectonic plate boundary where the Nazca plate moves beneath the South American plate. Stress accumulates along this boundary until it is suddenly released by movement of the plates during an earthquake. The portion of the plate boundary that moves, called the earthquake’s rupture zone, can stretch hundreds of kilometers. Stress is relieved in this zone following an earthquake but it may increase elsewhere.

Jian Lin and Ross Stein used GPS measurements of tectonic plate motion to estimate changes in stress from the 1960 event and found that stress had greatly increased just north of the 1960 rupture. They predicted that this region would be the next portion of the plate boundary to produce a large earthquake in Chile. Sure enough, last Saturday  the 2010 earthquake picked up where the 1960 earthquake rupture left off.

This sort of progression also occurred after the December 26th, 2004 magnitude 9.0 earthquake in Sumatra, when it was followed by a magnitude 8.7 earthquake on the southern end of the rupture zone just 3 months later on March 28, 2005. “The only difference is that it took 50 years for the northern neighboring section of the 1960 [Chile] earthquake to rupture, while it took only 3 months for the southern adjacent segment to rupture in Sumatra”, Lin noted.

Lin believes that the Haiti earthquake similarly transferred stress further east along the Enriquillo Fault which broke on Jan. 12th, but it would have had no effect on the stress state in Chile.

Lin and Stein also used their method of measuring stress changes to assess which faults in the San Andreas region of southern California are most likely to move next, but only time will reveal the accuracy of their predictions there. It seems as though we are another step closer to understanding and anticipating earthquakes, rather than thinking of them as freak events.

Sources:

Lin, J, and Stein, R.S., 2004, Stress triggering in thrust and subduction earthquakes and stressinteraction between the southern San Andreas and nearby thrust and strike-slip faults: Journal of Geophysical Research, v. 109.

http://www.whoi.edu/page.do?pid=7545&tid=282&cid=69866&ct=162

Mud volcano (debate) still hot nearly four years later

By Marci Wills,   Feb 19, 2010

When I first heard the highly scientific term “mud volcano” I thought it sounded awfully lame, but those in Indonesia would likely argue otherwise. On May 29, 2006, a mass of boiling mud unexpectedly erupted from beneath the densely populated Sidoarjo district of Java. The “Lusi mud volcano” (a conjunction of Lumpur, the Indonesian word for mud, and Sidoarjo) killed 13 people in 2006 due to ruptured gas pipelines and displaced an estimated 30,000 more. I vaguely remember hearing about this back when I was graduating from high school. So I was rather shocked when I learned this week, in my senior year of college, that the Lusi eruption hasn’t stopped!

The Lusi mud volcano erupting two days after its birth. From Mazzini et al (2007).

Nearly four years later, the mud volcano continues to ooze at an alarming rate of 160,000 cubic meters of 100°C mud every day (enough to fill 50 Olypmic-sized swimming pools!) It covers an area of 7 square kilometers (~3 square miles) up to 20 meters (65 feet) deep. The muck has defeated all efforts to thwart it, including dams, levees, drainage channels, and even attempts at plugging the center with large concrete balls. The volcano shows no signs of slowing, much less stopping, and researchers estimate it could continue to erupt for several decades. Naturally, a lot of people want to know why it happened.

Lusi is one of the largest examples of about 700 recognized mud volcanoes throughout the world. (Although the number varies depending on definition. Do you call a 1 meter high mound that seeps every so often a mud volcano too?) In addition to Indonesia, they are concentrated in Azerbaijan, Turkmenistan and the South Caspian Sea, often in regions associated with petroleum deposits. Mud volcanoes form when a large volume of water, mud, clay and gas becomes trapped underground. These liquid chambers can sit under very high pressures for millions of years until until they suddenly find a pathway to the surface.

Homes in Sidoarjo flooded by the mud

Two possible triggers have been identified for the Lusi mud volcano; a magnitude 6.3 earthquake which occurred 2 days earlier on May 27th, 2006, 250 km away in Yogyakarta, and a gas exploration well located only 150 m from the eruption. The drilling firm Lapindo Brantas has desperately refuted claims that poor drilling practices in their well lead to the eruption, while many other independent scientists try to prove them wrong. The resulting debate has seemingly quadrupled research on mud volcanoes, while delaying the establishment of liability and compensation to thousands of people affected.

The dispute culminated just this last month (February, 2010) in two studies from the opposing sides. Nurrochmat Sawolo, senior drilling advisor to Lapindo Brantas, and his colleagues asserted their claims in the journal Marine and Petroleum Geology, blaming the Yogyakarta earthquake for the eruption. An international team of scientists from the UK, USA, Australia and Indonesia, lead by Michael Davies of the Durham Energy Institute, responded with a paper in the same journal, providing the most definitive evidence yet that the well was the source of the drilling.

The Davies team found that the Yogyakarta earthquake was too small and distant to have triggered the Lusi mud volcano; the forces felt from the earthquake 250 km away in Sidoarjo were less than those felt there normally simply by weather and the tides. They also cite an on-site daily drilling report which states that Lapindo Brantas successfully pumped drilling mud back into the well immediately after the eruption to slow it. “The observation that pumping mud into the hole caused a reduction in eruption rate indicates a direct link between the wellbore and the eruption”, Davies says.

Such definitive evidence that the well caused the Lusi volcano is expected by many to resolve the debate, but what will legally come of the disaster remains to be determined. Either way, Lusi will surely continue to make its own muddy statement for years to come.

The area covered by the Lusi Volcano seen from the air in May, 2009.

Sources:

Sawolo, N., Sutriono, E., Istadi, B.P., and Darmoyo, A.B., 2009, The LUSI mud volcano triggering controversy: was it caused by drilling?: Journal of Marine and Petroleum Geology, v. 26, p. 1766-1784.

Mazzini, A., Svensen, H., Akhmanov, G.G., Aloisi, G., Planke, S., Malthe-Sørenssen, A., and Istadi, B.P., 2007, Triggering and dynamic evolution of the LUSI mud volcano, Indonesia: Earth and Planetary Science Letters, v. 261, p. 375-388.

http://www.eurekalert.org/pub_releases/2010-02/uoc–set021110.php

http://www.sciencedaily.com/releases/2010/02/100211211442.htm

http://www.nce.co.uk/mud-wrestling/5209733.article


Paleontologists discover dinosaurs with surprising colors

By Marci Wills

As a student of both geology and biology, it’s exciting when I hear about research integrating these two very diverse fields. So I’ll report a bit of paleontology news for this first week. And there’s not a topic in paleontology much more exciting than dinosaurs right?

Dinosaurs were a great subject to draw when I was in elementary school in the 90s because, as my art teacher cheerfully pointed out, “nobody knows what color they are, so you can color them however you’d like!” But the future of interpretive dinosaur drawing is looking a little less optimistic for children today, thanks to a study published online in Nature this week.

Sinosauropteryx fossil (The Nanjing Institute)

An international team of paleontologists from the Institute of Vertebrate Paleontology and Paleoanthropology (Beijing), the University of Bristol (UK), University College Dublin and the Open University (UK) revealed the first ever evidence for the color of dinosaur feathers. Yes that’s right, feathers. The feathers were those of early Cretaceous Therapod dinosaurs, a group thought to be the evolutionary stem group of modern birds. The suborder Therapoda contains those famous carnivores Velociraptor and Tyrannosaurus rex, but some of the group’s genera were rather less daunting. For instance, Sinosauropteryx measured only ~27 inches in length. It had simple feather-like bristles, precursors to flight feathers of modern birds, running down the length of its back and tail.

It was in fossilized remnants of these bristles from the Liaoning province of northeast China that the paleontologists found clues to their color. Pigmented organelles called melanosomes give color to the feathers and hair of modern birds and mammals, and because they are imbedded within a protein structure, they are highly resistant to deterioration. Although the pigments themselves had long since decayed, the team used powerful scanning electron microscopy to recognize surviving melanosomes by their shape in early Cretaceous bird and Therapod fossils over 100 million years old.

The fossils contained two types of melanosomes; sausage-shaped eumelanosomes, which contain black pigment found in the stripes of zebras, and spherical phaeomelanosomes, which contain the red pigment of red tailed hawks and some human hair. The distribution of these melanosomes led the paleontologists to believe Sinosauropteryx had alternating bands of orange and white feathers down the length of its tail! The study also reports that individuals of another small Therapod genus, Sinornithosaurus, varied in color from orange to black.

Early Cretaceous fossilized feather in which melanosomes were found. (Zhang et al, 2010)

More importantly, such findings further strengthen the argument for the evolution of birds from Therapod dinosaurs. The identical morphology of melanosomes from Therapods to very early birds and modern birds confirms that these bristles are related to modern flight feathers and not, as some skeptics believe, partially decayed collagen fibers.

Such evolutionary progression also suggests that feathers evolved before wings and therefore must have served some purpose other than flight. Sinosauropteryx only had feathers running down the crest of its back and tail, so they  would have had limited function in insulation. Mike Benton of the University of Bristol believes these dinosaurs were making a visual statement, noting that, “you don’t have an orange-and-white striped tail for nothing”.

The study found no evidence of other colors such as purples, yellows and blues. The proteins producing these colors degrade more easily than the black and orange pigments protected in organelles. So it seems that the dinosaur coloring books will remain largely open to interpretation, at least for now.

Artist rendition of a living Sinosauropteryx, by Jim Robbins

Sources:

The Paper: Fucheng Zhang, Stuart L. Kearns, Patrick J. Orr, Michael J. Benton, Zhonghe Zhou, Diane Johnson, Xing Xu, and Xiaolin Wang. Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds. Nature advanced online publication, 27 January 2010.

http://www.bris.ac.uk/news/2010/6806.html

http://www.nature.com/news/2010/100127/full/news.2010.39.html