Category: Web Resources

Depending on when fully modern humans left Africa – and that itself depends on evidence that is at odds with any definite resolution – the forebears of the eventual colonisers of the rest of the world may, or may not, have had to survive the effects of the biggest volcanic eruption of the past 2 million years. Around 74 ka the huge, elliptical caldera lake at Toba in Sumatra was formed by a stupendous eruption that threw out 800 km³ of ash (see Ash Wednesday to put this in perspective with recent events). Toba deposited a 15-centimetre ash layer over the entire Indian subcontinent. Toba has taken on a near iconic status among some palaeoanthropologists as a possible means of reducing the entire human population to a mere few thousand: a genetic ‘bottleneck’ that could have led to rapid evolution among surviving generations that shaped such things as language and culture. Unsurprisingly major efforts are underway to get hard facts about the relationship of fully modern humans to the Toba event, a lot of the work-in-progress being outlined at toba.arch.ox.ac.uk/index.htm.

See also:  Balter, M. 2010. Of two minds about Toba’s impact. Science, v. 327, p. 1187-1188.

The success of the online encyclopaedia called Wikipedia stems from millions of people being able to write about their own expertise, and also to add to, revise, correct and update any entry. Building up a knowledge base that way is a lot faster and more agreeable than individual efforts. The authors of a useful website on fossils (www.palaeos.com), begun in 2002, recently ran out of steam. Rather than allow it to become fallow, they have turned it into a wiki (wiki wiki means quickly in the Hawaiian language) at www.palaeos.org. Hopefully it will grow explosively, and I have suggested to  Prof P.U. Siffli, of Sringeri University in Karnataka, India, that he should contribute his hitherto private but astonishing knowledge on fossil hamsters.

The US Geological Survey has recently launched its Natural Hazards Gateway at www.usgs.gov/hazards to give access to data and educational material on volcanoes, landslides, hurricanes, floods, earthquakes, tsunamis and wildfires. The coverage is global, naturally with a great deal on the US. The links within USGS and to other agencies are comprehensive. When USGS sets out its stall, it groans with produce.

Have you exhausted the possibilities in Google Earth – unlikely – then why not try Google Mars (www.google.com/mars)? Well it’s a bit early, as the site is still under construction, and does not yet include the features that enrich the Google Earth experience or the full planetary surface. Nevertheless the University of Arizona, which produced the data mosaics, has provided a bright, colour-coded elevation map and mosaiced images in visible and infrared wavelengths that show enough detail to easily examine many of the landforms for which the ‘Red Planet’ has become renowned.  It is a fine resource for targeting users to find specific kinds of feature – craters, dunes, water-carved valleys and lava flows. Once complete it should satisfy anyone who wants to explore, probably including those with delusions of ‘boldly going…’ before they become too old and infirm….

Breathing life into ‘Snowball Earth’

Paul Hoffman’s hypothesis of episodes, mainly in the late-Precambrian, when Earth was encapsulated in ice from pole to pole has taken repeated knocks since he first proposed it. It seems only natural that he should make the evidence and his ideas more publicly available on the Web – http://www.snowballearth.org. ‘Snowball Earth’ is a live and important aspect of geoscientific debate, for a whole raft of reasons, and it continually evolves. Although Hoffman does use the site as a vehicle for rebuttals to all the objections that further research has raised, it is a great deal more interesting and useful than that: a very well produced resource for anyone interested in a crucial period – the Neoproterozoic – in the evolution of life. Additionally, it helps budding geoscientists come to grips with the intellectual and experimental processes involved in major advances in knowledge and understanding. Besides which, it will save Hoffman a small fortune in air fares to have his say to live audiences!

Launched in July 2005, Google Earth (earth.google.com) has become familiar to many Earth scientists.  Some, like me, may have needed encouragement to try it out. Whatever, once up and running on a modern PC with Windows 2000 or XP and broadband connection, even the free version of the software that you need to access Google Earth is compelling, even addictive.  It takes no more than a few minutes to realise that it revolutionises teaching of many aspects of Earth science, and will be used too as a top-line research tool by anyone interested in spatial data.

Based primarily on natural-colour images that cover the entire Earth, much at Landsat TM 15-30 m resolution but for some areas using other images that resolve to the order of a couple of metres or better, Google Earth also uses global topographic elevation data. This is where it takes on its revolutionising role.  It is easy to view the surface of any part of the planet in oblique perspective, when all topographic and a great many geological features show up dramatically. It is the ultimate ‘Swiss Hammer’ – mapping the complex geology of the Alps was only possible by viewing exposures in one massif from the vantage point of another. Choosing appropriate zoom factors connects geological features that are on different scales. Design of the database – it is perfectly seamless, except where resolution changes in mostly urban areas – makes it possible  at broadband connection speeds to roam in real time at any scale. This allows you to simulate flight at any altitude and with any downward look angle: ‘grand tours’ to visit all the famous geological sites you have longed for on every continent become simple. The novelty of 3-D simulation also means that there is much to discover.

Sometimes, even in one’s homeland, it is possible to get lost, especially at large scale. By turning on GIS layers for rivers and roads (in many areas populated places, even street names and fast-food outlets show) navigation is made easier. It is the linking of images with other kinds of data that gives Google Earth its potential for research power. Designed as an easy-to-use geographic information system, by purchasing professional versions of some GIS software you can add layers interpreted, almost literally, ‘on the fly’ (Butler, D. 2006. The web-wide world. Nature, v. 439, p. 776-778).

An immediate attraction, both for globe-trotting geoscientists and, more importantly, people engaged in disaster relief, is the way Google Earth makes it easy to become familiar in moderate detail with the terrain that has to be faced. Solving problems of access, assessing where assistance may be most urgently needed is helped enormously by its highly realistic geographic visualisation. Of course, it cuts down the need for very expensive helicopter reconnaissance.  Google Earth has already proved invaluable for assessing the aftermath of the October 2005 earthquake in Kashmir. Google facilitates the mosaicing of new images of disaster areas, such as those struck by Hurricane Katrina, and their incorporation into the Google Earth database (Nourbakhsh, I. 2006. Mapping disaster zones. Nature, v. 439, p. 787-788).

A few people get frightened by some of the highest resolution images that are available – even the lines on tennis courts show up – as if their privacy was being invaded. More seriously, some governments worry about security implications of anyone being able to see intimate details of airfields and ports.  That is silly – at any time the Quickbird or Ikonos satellites can take a snap of any part of the planet at up to 65 cm resolution for anyone who has the cash to pay for its acquisition; most likely intelligence agencies and military strategists. Privacy, at least from several hundred kilometres above, is a thing of the past.  Every geologist would like to get one-metre resolution images of their research areas. If they see something intended to be hidden for one or another reason, they have an obligation to be discrete.

One of the most exciting geoscience websites that you can find is hosted by Arizona State University in Tempe.  It centres on the capture of thermally emitted infrared radiation from the Martian surface by the Thermal Emission Imaging System (THEMIS) aboard NASA’s Mars Odyssey orbiter (http://themis.asu.edu). The opening ‘splash’ features thermal images gathered on the fly by THEMIS, as if you were peering down from the spacecraft as it orbits the planet. The movies are not really live, but about 2 weeks old. Nevertheless, they have a hypnotic appeal as one waits to see what is going to turn up – mainly small craters, but sometimes oddities such as the strange terrain of the northern Tharsis Basin that is a tangle of extensional faults that might well be on the floor of the Afar Depression in north-eastern Ethiopia. THEMIS acquires data in several thermal wavelengths, and this is its scientific importance: the multiple channels span the very different emission spectra of silicate minerals.

Using different thermal bands to control the red, green and blue colour guns of a video monitor produces vivid images that are colour-coded for a variety of rock compositions. The great advantage of thermal sensing is that it works at night as well as during the day.  So THEMIS images can also tell us a great deal about the way in which rocks heat up and cool, which is another clue to their composition.  Having no clouds – there are seasonal dust storms – Mars can be mapped in great geological detail without geologists having to traipse across space and the inhospitable Martian surface.  All that a human touch could add would be to bring back some rock samples for geochemists to get their teeth stuck into. What those rock are – basalts, andesites and various sediments – is already becoming known in greater detail than for huge tracts of the Earth’s surface.  Fortunately, a sister instrument to THEMIS, called ASTER does orbit the Earth to deploy a similar multispectral thermal imaging system.  What is hugely annoying is that the Martian data are 5 times sharper than those of the infinitely more interesting Earth.  Yet again, NASA has priorities that that are far from those of most of humanity.  One excuse regularly given for better resolution from other planets is that of security issues for Earth images….

Virtual field trips made possible by the considerable ingenuity of their authors are excellent means of taking school children and even undergraduates to places well off limits or resources. Most are available only on CD or DVD, but those on the web are especially valuable for all with sufficient connection speed to use them. A Swiss educational organisation hosts the work of Italian volcanologists Roberto Carniel and Marco Fulle with Swiss teacher Jürg Alean.  They make it possible to experience volcanological life vividly, by ‘visiting’ the famous Stromboli, Ethiopia’s Erta Ale lava lake, explosive Montserrat in the Caribean and others.

Visit http://www.swisseduc.ch/stromboli

A measure of the quality of a science website, apart from its visual appeal, is a mixture of how much it teaches you and what you can snaffle to help teach others. As a point of departure for E-geology, it will be hard to beat the Smithsonian Institutions geotime site (www.nmnh.si.edu/paleo/geotime). That’s because it focuses first on the history, and if you care to you can discover how that was constructed from the geological record. Its central organiser is a slider that can be zoomed, which lays out the geological past – the literal time line divided into stratigraphic Eons, Eras, Periods and Epochs. Each division is clickable, although zooming in several times is needed to see the Cenozoic Epochs. But, hang on, there is no Ediacaran Period, the newest addition, nor the subdivision of the Proterozoic on the timeline. Whatever, clicking on a division opens a thumbnail sketch of each and links to pages that give more detail on the highlights, plus introductions to the founding concepts behind geological time and unravelling Earth and life processes. There is a glossary, which shows the influence of Encarta and Wikipedia. Here is a chance to learn for hours in a most convenient and engaging way, but graphics are few and far between in the various main panes. There are examples of important fossil organisms, but displayed at a size that lacks satisfying detail. What the site needs are maps and explanatory diagrams, which are available elesewhere. So the Smithsonian needs, I think, to liase a bit with other learning resources in the geosciences. It would be good to have a one-stop shop.

Earth Pages News of June 2005 reported on the development by the US Geological Survey of the first daily seismic forecasting service, which covers California.  It has a web site at http://pasadena.wr.usgs.gov/step.   The forecast is for events, generally aftershocks of earlier earthquakes, with sufficient energy to throw objects off shelves (Modified Mercalli Index VI). On June 30 2005, Lake Tahoe had a chance around 1 in 100 of such a tremblor, with the length of the San Andreas and related fault systems highlighted at between 1 in 10 000 to 1000.  Of course, it will take some time before people link as quickly as they do to the weather forecast.

Growth rings in tree trunks are among the best records of local climate variation that there are: they provide an annual “stratigraphy”.  So intricate are the records that it has proved possible to match ring sequences in ancient but still growing trees to those found in logs of even greater antiquity, thereby building up a “dendrochronology” that extends back into history.  Tree rings help historians link human affairs to a background of changing conditions for life.  Henri Grissino-Mayer of the University of Tennessee has brought together a wealth of dendrochronological information in his Ultimate Tree Ring Pages at web.utk.edu/%7Egrissino/default.html.

There are so many places one might wish to visit for their scenery and physical geography, yet only limited resources and, of course, time.  The availability of high-resolution satellite images, together with free data that show variations in topographic elevation newly released from the Shuttle Radar Topography Mission, enables realistic simulations of just about anywhere.  William Bowen of the California State University has exploited this opportunity to give all-comers a view of most parts of the land surface, as if they were looking obliquely downwards from a high-altitude aircraft – geogdata.csun.edu/world_atlas/index.html

Mineral wealth

Although there are many glossy books about museum quality mineral specimens, as well as being expensive they often only cover a selection of those minerals known to science.  One of the beauties of the web is that a site can cram in as many pictures and ancillary data as its server permits, and anyone can browse what is on offer.  One such site has been set up by consulting geologist David Barthelmy, which not only illustrates more than 2000 different minerals (half the site’s content of 4300) but allows users to examine their molecular structure interactively – webmineral.com

Most of us have grown used to thinking that earthquakes have an epicentre at some fixed point beneath the surface. That is not at all true, as the event that set the Boxing Day 2004 tsunamis in motion as been shown to have been a lengthy rip that propagated from Sumatra NNE to the Nicobar Islands, over a period of about an hour.  Even quite small earthquakes are distributed and often migrate along a fault line.  Christine arson of the University of Colorado has captured what is effectively a movie of a magnitude 8.3 event off the island of Hokkaido, Japan, which can be viewed at spot.colorado.edu/~kristine/tokachi_rupture.gif. The data that she used comes from a network of  a thousand highly sensitive GPS receivers set up throughout Japan.  Instead of acceleration, measured by conventional seismometers, GPS records actual position in x, y, z coordinates.  That enable the actual motions to be imaged as in  the movie.

It is a plain to me as to any reader that EPN  is eclectic, and in some cases pretty impressionist; how else to write a monthly weblog about the broad spectrum of geoscientific developments?  So it is good to see websites with a much narrower focus, yet that manage to inform entertainingly and provocatively.  Such a site is www.mantleplumes.org, organised by Gillian Foulger of Durham University, currently a visiting scientist with the Volcano Hazards Team at USGS, Menlo Park, USA.  It covers the whole of “plumeology”; the tectonics, the magmatism, ages and wider features, even ideas about the presence or absence of plume-related features on other planets.  It has some powerful contributing essayists, such as Don Anderson and Warren Hamilton, who are not averse to scepticism and critiques, and represent work in progress on a book, Plates, Plumes & Paradigms just submitted to the Geological Society of America – a rare event to see preprints of book chapters.  It serves an educational role as well, with well-illustrated and up-to-date reviews of the mechanisms involved in large-igneous provinces., and thumbnails on a continent-by continent basis. Jason Morgan came up with the “hot-spot” idea about 33 years ago and launched a revolutionising force in plate tectonics.  It is good to see that there is still a vibrancy about the topic.

Ancient art

The hallmark of modern human’s abilities is the art left behind by our ancestors since about 30-40 thousand years ago.  Among the most enigmatic are those by Australian native people, that might date back as far as 50 ka.  The first were discovered by Joseph Bradshaw and his brother in the Kimberly Ranges of northern Western Australia in 1891.  The Geneva-based Bradshaw Foundation (http://www.bradshawfoundation.com/) is developing a comprehensive archive of rock-art images from across the globe, which will uplift anyone who visits it.

Three web sites that have been suggested are well worth browsing.  Bernie Gunn has assembled a monumental database of the geochemistry of volcanic rocks at http://www.geokem.com .  That, in itself,  is a magnificent resource for anyone working on the topic, but the site also has a comprehensive guide to good laboratory practice that will be invaluable to anyone beginning to work in the field., plus a host of good reference material and links.  Its quality is hardly surprising since Bernie has been engaged in geochemical research for more than 3 decades at the University of Montreal.  Another dimension to geological web resources is revealed by that compiled by Fettes College in Edinburgh at http://www.fettes.com/shetland .  It is an encyclopaedic source of environmental information on one of Britain’s many microcosms of Earth science.  It ranges from the Shetland Isles’ long geological evolution to its present geomorphology.  Fettes is a private school, with a glittering roll of alumni.  Equally encyclopaedic is http://paleodb.org , which is as near to a global database of palaeontology as you can get at present.  One of the highlights is being able to plot occurrences at the genus and species level on interactive maps, as well as browse and analyse the contents statistically.  Users do need to know how to spell taxonomic names!  Once you have compiled a map (the only trilobite whose name I can spell is Dalmanites!), you can zoom in.  If you click on an occurrence up comes a summary of the locality, with links to other parts of the database, including other fossils at the locality.  Wisely, location detail is crude enough to deter collectors from ravaging sites.  The database is compiled by 140 contributors in 11 countries.  This a site for specialists, but a beginner can learn a great deal from it.

Information on mineralogy is often hard to find on the web, so the University of Wurzburg Institute of Mineralogy in Germany has created a comprehensive set of links that cover a wealth of topics.  They include teaching materials at different levels, information on experimental and analytical techniques, thermobarometry, mineral descriptions and crystallography, economic mineralogy, gemmology and much more besides.  Go to http://www.uni-wuerzburg.de/mineralogie/links.html

This seems to be a blog well worth examining and mining – www.talkorigins.org/faqs/homs .  The blogger, Jim Foley, maintains an excellent sense of humour as well as what appears to be considerable energy and knowledge.  There is a link to a masterful April Fool’s Day joke at the expense of the Institute for Creation Research, which gulled their radio show, Science, Scripture and Salvation in 2000 into accepting at face value a spoof article in the April 1997 issue of Discover magazine.  This was penned by the German palaeoanthropologist Oscar Todkopf (Deadheads are fans of the Grateful Dead) of Hindenburg University (Led Zeppelin and a well-known, flaming bag of gas), which documented a find of assorted musical instruments, (a 6 foot length of mammoth tusk turned into a tuba, a bagpipe-like instrument made from the bladder of a large animal, a triangle of thin bones, a collection of hollowed out bones of different lengths, which Todkopf suggested might be part of a xylophone (he called it a ‘xylobone’), the first known Neanderthal cave painting, showing marching musicians alongside some suspected musical notation, and a Neanderthal skull) in the famous Neander Valley, Germany. Even the fact that the eponymous author claimed that Neanderthal musicians played the bagpipes with their remarkably huge noses, did not deter the ICR’s Marvin Lubenow, author of the leading creationist book on human origins, Bones of Contention, from commenting, “There’s overwhelming evidence that Neanderthals were musically inclined.”, along with a further stream of howlers.  For that alone, you must visit this site.  However, it is probably the best source of human-origins information, illustrations and news that there is on the Web, and puts the EPN anthropology and geoarchaeology section to shame!  There is a balance, for the site includes a great many items on creationist ideas, but this has to be tongue in cheek, despite the accuracy of the accounts there. I wonder who Jim Foley is….

Algorithms that model the physical effects of extraterrestrial impacts from the Lunar and Planetary Laboratory of the University of Arizona, headed by Jay Melosh, have been assembled into a handy on-line calculator, with notes on the processes involved.  If you want to find out if you will be fried, buried or blown to smithereens (probably all three if our luck is really out), and the chances of being harmed by alien lumps of rock or ice, you can find the calculator at http://www.lpl.arizona.edu/impacteffects/ .  It is not recommended for estate agents, because, unlike many other disastrous events, impacts can be anticipated anywhere.

The US Geological Survey has made publicly available a large repository of geochemical data (63 of the 91 naturally occurring elements) that it has acquired through a continuing nation-wide survey of stream sediments (available at http://tin.er.usgs.gov/geochem/doc/home.htm).  The data coverage is incomplete and involves several generations of previous surveys.  The most revealing stream sediment surveys involve collection of panned sediment samples in every small stream that has no upstream tributary, but that is a daunting task for such a vast area as the USA.  That method allows the analyses to be treated as accurate representations of stream sediment composition in upstream catchments around 1 x 1 km in size.  The USGS data are a mixed bunch, some dating from the National Uranium Resource Evaluation (NURE) of the 1970s when there was a scramble to find new uranium ore bodies.  The NURE survey involved a sample density based on a 17 x 17 km grid, and made no distinction between stream order.  The latest USGS survey is based on sample collection that uses 10 x 10 km grids drawn in the UTM co-ordinate system. Each 10 x 10 km cell is divided into four quadrants, and one is selected at random for sampling.  In that one small stream selected at random is chosen for analysis.  The data set is too coarse and too varied to create meaningful gridded interpolations that can be displayed as continuous tone images, unlike comparable geochemical atlases based on systematic, small-stream sampling, such as that developed for commercial leasing by the British Geological Survey. The NGS data will be a useful resource for scanning broad geochemical features of the country, such as for high levels of potentially toxic elements in water, bearing in mind that the analyses are of solid minerals not the water itself.

“Plumeology” site

The last issue of EPN showed that the debate over mantle  plumes, their sources, and even their existence is hotting up (see Geoscience consensus challenged in EPN January 2004).  However that pans out, vast areas of continental and submarine flood basalts compel geoscientists to ponder over them, the more so because they represent events never witnessed by humans and are therefore unimaginable.  Now they have their own website (http://www.mantleplumes.org/) that has been compiled by Gillian Foulger of Durham University.  It is an impressive and highly useful resource, the outstanding feature being pages on most aspects of large igneous provinces written by experts who are also excellent communicators.  There is even a linked site at the Geological Society that hosts discussion on the Great Plume Debate, as well as a letters page, links and up to date news.  For information, without unnecessary frills, this is the place to go, especially if you have to write an essay!

If you like that frisson of fear that comes from contemplating the demise of the world as we know it, then the Near Earth Objects Dynamic Site (NEODyS) will give you hours of it (newton.dm.unipi.it/neodys).  The more than 2500 NEOs that orbit within 45 million km of the Earth’s are fully catalogued there, along with impact risk assessment.  The site also links to the on-line newletter Tumbling Stone, that has news on asteroidal matters, especially near misses…..and impending doom…..

They are all at www.dinodata.net, seriously!  Dutch enthusiast, Fred Bervoets puts a vast resource and copious links at anyone’s disposal, even including a forum and a chat rooms.  Technical drawings and artistic impressions of many species are there, together with guides to where specimens can be seen in museums, and major fossil sites.  Skin, eggs, diet, controversies, companion species and sources for replicas……

The Smithsonian Institute’s National Museum of Natural History has a new and evolving Earth science website at  www.mnh.si.edu/earth (Flash 6 and printable versions).  Currently only the Rocks and Mining section is up and running, but it is instructive at the introductory level.  To come are sections on gemstones, plate tectonics and the Solar System.  There are also downloads and a geogallery.  It is somewhat slow in Flash using a normal dial-up connection., but the printable version has no images.  With a fast connection, this is likely to become a favourite for elementary visualisation of Earth processes.

The University of New Brunswick, Canada, maintains an illustrated archive of information on terrestrial impact craters.  It lists 169, with exact co-ordinates for each and much other information besides.  Many have satellite, aerial and/or ground images, plus full lists of references for each.  The URL is http://www.unb.ca/passc/ImpactDatabase/