Category Archives: 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 – 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 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.