Thursday, January 29, 2009

Panchgani Tableland Informs About Western Ghat Uplift History

And the answer to the earlier puzzler I posed about the thick dark layer seen capping a basalt summit is... Ferricrete - popular name Laterite. These iron enriched hard crusts cap high basalt summits along the Western Ghats and along with similar surfaces of chemical weathering which occur at different altitudes tell us about the long and episodic uplift history of the Western Ghats.

The west coast of India is a high elevation passive margin that formed when India broke away from first Madagascar around 88 my ago and then Seychelles around 65-70 my ago. The Western ghats is a north south trending mountain range parallel to the west coast of India. It is characterized by a spectacular west facing escarpment and very youthful relief which suggest recent and ongoing uplift. The ghats are composed of Deccan Basalts in the north and Precambrian granulites in the south.

Right, so here is what a typical ferricrete cap on basalt looks like. It forms mesas, like the one in the image below of Panchgani tableland, a popular tourist destination.


Source: E-Journal Finn-India

So, how does ferricrete / laterite form? This material is formed by the impregnation of weathered rock by iron oxides and hydroxide. During prolonged chemical weathering, more soluble elements within the basalt like, Calcium, Sodium, Magnesium, eventually Silicon get transported away in solution and the more insoluble iron hydroxides are left behind. These iron composites get hardened on exposure to air and form crusts.

There are two explanations of how they form Mesas like the Panchgani tableland. The schematic below shows the two mechanisms.


Source: Ollier and Sheth 2008

1) A period of chemical weathering along a widespread area of basalts formed a continuous blanket of ferricrete. Subsequent erosion of most of it left discontinuous patches. 2) The ferricrete formed in shallow flat bottomed river valleys that developed on the basalt surface. The alluvium and colluvium of these basalt valleys got converted to ferricrete. The surrounding highlands got eroded away being softer than the ferricrete. The mesas represent an "inversion of relief". Former valley bottom now standing in higher relief.

I am a little biased towards the inverted relief as far as the ferricrete mesas in the north part of the Western Ghats go. The southern laterites developed on the Precambrian granulites are most probably remnants of blankets. But in this case I am persuaded more by the outcrop geometry of the ferricrete mesas.

Take a look.

Source: Ollier and Sheth 2008

Now, isn't that cool! They occur as a long stringy line of mesas (dark patches) outlining a dendritic pattern, just like a river system. This ancient river system if the interpretation is correct flowed in a northerly direction. Today the drainage east of the continental divide is in a southeasterly direction. So as the Western Ghats rose there must have been differential uplift which reversed the drainage direction as well.

What was once a river system is now preserved as a chain of Mesas standing at 1500 m ASL. Tell me you don't think earth processes are awesome after thinking through this.

Okay, so ferricretes are chemical weathering products but what has that to do with the uplift of the Western Ghats. The problem with the Western Ghats both the basaltic section and the PreCambrian section is that there are no obvious structural indicators like fault scarps or structually offset marker horizons that can indicate uplift history.

But surfaces of intense chemical weathering are important. They form during times of tectonic stability. The Panchgani ferricrete tells us that after the eruption of the Deccan Basalts in the latest Cretaceous there was a long period of intense chemical weathering in a tectonically stable regime. No uplift at all. If blocks of crust are being actively uplifted they will erode into facets and form sharp peaks and V shaped valleys. Weathering on a stable block of crust will form flat surfaces or peneplains or planation surfaces which is what the Panchgani tableland and other such surfaces further south are.

If there is episodic uplift alternating with periods of stability then there will be development of such flat weathering surfaces at various altitudes as mountain ranges rise and get weathered and beveled and then rise again. The younger surfaces will occur at lower altitudes.

The diagram below helps conceptualize this.

Source: MantlePlumes.org

This is precisely the pattern you see along the length of the Western Ghats. The older planation surfaces occur at the highest altitude and the younger ones at lower altitude. Along the western coastal plains there are ferricrete surfaces of mid Tertiary age which occur at higher relief than the surrounding plains and testify to the ongoing uplift of the region.

The image below shows a north south transect along the summits of the Western Ghats from Panchgani (1500 m) in the north to Anamalai (2695 m) in the south.


And the figure below is the cross section.


Source: MantlePlumes.org

Look at the multistory benches that have developed episodically as the Western Ghats rose to their present heights. A series of planation surfaces (S0 - S4) indicating periods of stability and chemical weathering followed by uplift.

Most of this uplift occurred in the Cenozoic. Planation surfaces below the Deccan pile (S0 - Mesozoic age) tells us that there was little pre-volcanic uplift. Planation surfaces directly above the volcanics (Panchgani ferricrete - latest Cretaceous- Paleocene) tells us that after eruption there was a period of stability. Uplift started later in the Cenozoic. An intial period of uplift in early Cenozoic which lifted the Ghats as well as the coastal plains was followed by a period of stability. Younger ferricrete on the coastal plains developed during this period of stability in the mid-Tertiary sit unconformably on coastal plain rocks indicating deformation and tilting of the coastal plain during the earlier phase of uplift.

We can time that uplift by looking at the sediments in the west coast basins in the Arabian sea. They show two major pulses of sedimentation in the Cenozoic, the first in the Paleocene and the second post Miocene. These basins contain about 109,000 cubic km of sediment. Numerical modelling of the west coast and ghat evolution suggests that most of the great elevation of the Western Ghats is best explained as an isostatic response of the lithosphere to denudational unloading of the crust onshore along the now coastal plains and sediment loading offshore. As erosion removed great volumes of sediment and dumped them in adjoining basins, the crust rebounded in response to the unroofing.

This theoretical work is supported by Apatite fission track thermochronometry which indicates that nearly 3-4 km of crust has been removed from the coastal plains and about 1-2 km from further inland. There probably was a elevation difference between the hinterland and coast, an artifact of the rift flank structure formed when India rifted from the Seychelles around 65-70 million years ago. But then differential erosion between the coast and the hinterland must have accentuated this existing topographic difference in effect generating the steep west facing escarpment and causing the escarpment to retreat eastwards forming the present coastal plains. Isostatic uplift contributed by further lifting the entire region resulting in the present day great heights and the youthful rejuvenated topography.

Isostacy doesn't explain all the elevation. Post Miocene compressional stresses from the Himalayan collision also affected this region resulting in minor deformation and uplift.

That's a lot to take in from a starting point of a flat weathered surface made up of ferricrete. I have been trekking in the Western Ghats long before I took up geology seriously. Now I look at these great heights with a more mature understanding but with an even greater sense of excitement.

Tuesday, January 27, 2009

A Walk In The Woods

My Book Shelf - 7

Last week I went for a hike in a reserve forest near the hill stations of Panchgani and Mahabaleshwar. It was part work too, I am giving geological consultancy to an ecological tourism company, so work and play together made for a fun experience. It was a perfect late January day. Bright sunshine but not too warm. I found the woods quite soothing unlike Bill Bryson who found the Appalachian woods somewhat dark and a little creepy.

Woods are not like any other spaces. To begin with, they are cubic. Their trees surround you, loom over you, press in from all sides. Woods choke off views and leave you muddled and without bearings. They make you feel small and confused and vulnerable, like a small child lost in a crowd of strange legs.Stand in a desert or prairie and you know you are in a big space. Stand in a woods and you only sense it. They are a vast, featureless nowhere. And they are alive.

I can agree with the alive bit. Its not yet spring in this part of the world. Come to think of it we don't have a very well defined spring. Winter just becomes summer in a matter of days. But the woods were blooming with flowers and fresh buds and leaves.


It felt like the spring woods that Bryson loves:

In a normal year we would be walking into the zestful bounty of a southern mountain spring, through a radiant, productive, newborn world alive with the zip of insects and the fussy twitter of birds- a world bursting with fresh wholesome air and that rich, velvety, lung-filling smell of chlorophyll you get when you push through low, leafy branches.

There was a biologist with us who kept up a steady stream of chatter about the botanical display in front of us. Non stop talking encyclopedia my friend concluded. I had to agree. He gave a really informative exposition on the plant life. How to distinguish between a Jambul tree leaf - Syzygium cumini and Anjani - Umbalatus memecylon.., which bees pollinate which flowers, and .. look at this leaf, Phycus exasperata. The surface is like sandpaper. It grows at the edge of the plateau along steep slopes. Abrasive enough to scrape the metal coating of a pen. Even goats avoid it. Damn, that's abrasive..

But he did not talk about evolution.

That was a conversation I was having with myself.

Oh....look at that Paradise Flycatcher. Too quick for my camera. Tails at least a foot long. ...Male. Sexual selection. why do only males develop elaborate ornamentation? Doesn't that depend on parental investment? If only one sex invests in child care that sex will be the choosy one. Females mostly. Males advertise their genes by evolving outrageous gear. Females evolve greater and greater discrimination of male ornaments... positive feedback... runaway selection. What if both sexes invest a lot in the children? W.D. Hamilton once remarked that if he understood why both sexes of a particular species of bird were brightly colored he would die happy.....Hmmm, he died of malaria contracted in the Congo...

Up ahead, .. interesting lichen on a tree. Two different species. One with a foliose form, leaf like and the other also plant like but forming fruit like bodies, fructiose form. The foliase form is the paler growth on the tree in image below. The fructiose is the golden brown clumps.


Source: Elements Eco Tours

..What's the term.... ya.. character displacement. When two closely related species cohabit the same geographic space, natural selection will favor traits that enable the two species to exploit different resources. ...That leads to rapid divergence in their form.

We walked and took short breaks.

Water?

No thanks

How about a chickoo?

Had a banana..

Right..

Yep...

Then there was a clearing in the woods. The cubic space surrounding us opened up and I saw a slope capped by a thick dark layer. Made me really stand there and think about the geology of the Western Ghats.


That layer you see is about 50-70 feet thick. It is one of the most important geological horizons of the Deccan basaltic province... and its not a basalt.

Can you guess what it is?

......Coming soon.

See: My Book Shelf

Wednesday, January 21, 2009

Evolution of Crust, Climate and Life: Skeletal Mineralogy

Why don't organisms use dolomite to build skeletons? A recent paper in Geology (open access) links crustal evolution and climate change as controls on skeletal mineralogy. It doesn't address my question on dolomite, but its quite interesting and informative work:

Carbonate mineralogies have oscillated between aragonite and calcite seas through geological time, proposed to be due mainly to secular variation in the magnesium/calcium ratio driven by changing rates of ocean crust production. A quantitative compilation of inorganic and biominerals from the onset of biomineralization (late Ediacaran–Middle Ordovician) reveals a correspondence between seawater chemistry and the first adopted mineralogy of skeletal clades.

The term calcite and aragonite seas implies that low-mg calcite is thermodynamically stable in calcite seas, while aragonite is stable under a higher mMg/Ca ratio of sea-water. Late Proterozoic (Ediacaran) to early mid Cambrian was a time of aragonite seas. Mid Cambrian to late Ordovician was a time of calcite seas. The figure below shows the oscillating sea water chemistry through geologic history.


Organisms use a variety of minerals to build skeletons around their soft tissue. Calcium carbonate in the form of three minerals,low Mg calcite (< 4 mole% Mg), high Mg calcite (> 4 mole% Mg) and aragonite are the most widely used materials for building skeletons. Silica and calcium phosphate is also used by some groups.

What this research shows is that oscillating sea-water chemistry from late Proterozoic to Ordovician, either changes in Mg/Ca ratio of seawater or changes in pCO2 driven by climatic changes from icehouse conditions to greenhouse conditions has influenced the adoption of specific carbonate phases as skeletal material. Here's the distribution of the mineralogy of major skeletal taxa and carbonate inorganic precipitates (ooids and synsedimentary marine cements) from upper Ediacaran to Middle Ordovician.


Organisms are pretty conservative about which clothes they wear. Once a skeletal mineralogy has been selected, organisms are loathe to change it. Corals are a famous exception. Paleozoic corals (Tabulates and Rugose) wore calcite armor. Mesozoic and Cenozoic corals have switched to aragonite.

Besides the changes from aragonite / high Mg calcite to low Mg calcite biota at various times as sea water chemistry changed, the figure also reveals an interesting pattern of metazoan evolution. Notice the greater diversity of metazoans using aragonite and high-Mg calcite. Actually the diversity is more than the figure shows, since a lot of the phosphate skeletal minerals are secondary, formed by early alteration of aragonite. And most of this diversity appears by early mid Cambrian before the switch to low-mg calcite seas.

That shows that by the end of Tommotian times the metazoan biosphere had greatly diversified with many clades acquiring an ability to secrete skeletons. Fewer new skeletal groups arose after the middle Cambrian during the time of low Mg calcite seas.

So, back to my original question. Why was dolomite left out of the organic wardrobe?

Dolomite is a Ca Mg carbonate. Mg content varies from 48 to 52 percent, sometimes more. It is not just high Mg calcite with more Mg. In mineralogy jargon, high Mg calcite and dolomite don't form a solid solution series. You can't make dolomite by simple adding Mg ions to the high Mg calcite lattice. In high Mg calcite the Mg ions substitute for Ca ions randomly throughout the unit cell. In dolomite there are MgCO3 layers alternating with a CaCO3 layers. There is almost no substitution of Mg for Ca and vice versa within layers.

There is usually plenty of Mg in seawater for dolomite to precipitate. The figure below shows the distribution of dolomite through the Phanerozoic. Most of this dolomite is diagenetic in origin formed by the replacement of earlier calcite phases.

You can see that dolomite peaks actually coincide with calcite seas i.e. sea water having lower Mg/Ca ratio.

So its not the lack of Mg that is the problem. The problems are kinetic.

Sulphate and phosphate ions in sea water inhibit or slow down dolomite precipitation. The environments where dolomite readily precipitates directly from sea-water and in fact forms a sort of a skeletal coat on microbial colonies is in supratidal flats and hypersaline settings. This is where sulphate reducing bacteria remove sulphate ions from solutions triggering rapid precipitation of dolomite.

But for the vast majority of organisms under normal marine conditions, dolomite is out of reach. Post Ediacaran times as metazoan ecosystems increased in complexity, skeletonization evolved most likely as a response to predation.

The hurly burly of predator prey interaction would have favored minerals that precipitate rapidly as a choice for building skeletons. Dolomite the slow poke of carbonate phases lost out.

I like these big themes. There may be a post series here, exploring these kind of complex causal chains linking crustal and climate processes to patterns of biological evolution. I might post a few on this topic in the future.

Monday, January 19, 2009

Are Geologists Unhappier Than Actuaries?

Via NPR Science Friday a ranking of best jobs you can have. The criteria considered? Stress, Work Environment, Physical Demands, Income and Outlook. No intangibles like the feeling you get after finding that prized fossil after a week long search in 100 deg heat.

Science jobs score high in this list. Several in the top ten. Mathematicians get the highest ranking. Geologists are ranked 30th. That is low in my admittedly biased opinion. But physical demands is one the criteria used, so that may have bumped geology to a lower ranking than many fields. In terms of salary /outlook geology compares well with fields ranked much higher.

The worst jobs are lumberjack and dairy farmer. And I thought all those French farmers making cheese looked quite happy on Discovery channel!

Well, what about those mathematicians? The list finds them to be the most satisfied with their career. And they do also have a high opinion of themselves.

Source: xkcd comics

But actuaries are second best?! That is actually quite close to a mathematics career. But still it's really hard for a geologist to accept that!

Thursday, January 15, 2009

Gearing up for Mr Darwin

As the bicentennial of Charles Darwin's birth and the sesquicentennial of the publication of The Origin of Species unfolds, no.... I am not about to start reading The Origin again. I did read it a few years ago, and continue reading a few sections now and then.

But I am reading two new blogs on Darwin. The first is by John Whitfield called Blogging the Origin. He is a science writer who fessed up he hadn't read The Origin. So he is blogging about his reading experience every few days. The second is a blog run by Science magazine. Don't need a subscription to read it. It's called Origins, a history of beginnings.

Also my alma mater Florida State University will be holding 2 week long celebrations in honor of the great man under a program titled Origins 09. Lots of talks and shows. Science Friday will host a special from Tallahassee on March 20th.

Is The Origin these days a phenomenon like Stephen Hawking's A Brief History of Time? Everyone nods reverentially on how great a book it is, but how many have actually read it? Certainly, it is not required reading for geologists. I guess though not many biologists have read it either. Biology and evolutionary theory has moved on over the last 150 years since The Origin and you don't need to read it to understand evolution. It would be very worrying indeed if you still had to rely on a 150 year old book.

Off course you can't do without it if you want to understand the history of evolutionary thought. You do get an immediate sense reading The Origin of how extraordinary a thinker Charles Darwin was. His insistence on accumulating as much evidence in support of his argument, his talent for detail, his visionary exploration of many fields near and far from his immediate area of expertise, and the realization that creeps on you of how right he was about so many of the important questions on evolution. All this makes reading The Origin still a treat.

Speaking of geology, David Bressan over at Cryology and Co. has a very nice post on Darwin the geologist. Geology did figure prominently in The Origin enough for a separate chapter of its own. Darwin used his knowledge of geology to ram home the point that the fossil record is incomplete as deposition of sediment is not continuous over space and time. There are taphonomic controls too on fossil preservation. So scientists should not expect to see a fine gradational series of fossil forms. He also understood the significance of unconformities and used it to explain why entire groups of new species appear suddenly in and disappear from the rock record.

A quote from the chapter Imperfection of Geologic Record:

For my part, following out Lyell's metaphor, I look at the natural geological record, as a history of the world imperfectly kept, and written in a changing dialect; of this history we possess the last volume alone, relating only to two or three countries. Of this volume, only here and there a short chapter has been preserved; and of each page, only here and there a few lines. Each word of the slowly changing language, in which history is supposed to be written, being more or less different in the interrupted succession of chapters, may represent the apparently abruptly changed forms of life, entombed in our consecutive but widely separated , formations. On this view, the difficulties above discussed are greatly diminished , or even disappear.

Who said Victorian English is a pain to follow? One long argument he called his book. And he won nearly all the arguments he made.

Monday, January 12, 2009

Have You Been Involved In Noisy Smelly Science?

My Book Shelf - 6

Have you done science that involves a lot of physical activity, puking, bleeding, nasty smells?

Still flipping through Jenny Uglow's The Lunar Men: Five Friends Whose Curiosity Changed the World and this passage about 1700's science stuck with me:

Science itself was intensely physical: medicine was a saga of bleeding and blisters; chemistry a matter of green fumes and red fumes, of the tang of acid on the tongue, of sneezing and choking and watering eyes. And this sensual bias was embedded in the terms they used: as chemical substances proved mysteriously choosy, reacting with some substances and repelled by others, so chemists hunted for "affinities", patterns of binding (and baffling) as choices in love.

As I recall my research days I wonder what has changed! My experience with science involved a lot of physical activity and a lot of noise. Hours of walking on outcrops, the wham of the sledgehammer on rock (Ordovician limestones of the S. Appalachians are very well cemented and hard) and the endless high pitched grind of the thin section cutting and grinding wheel. I made more than 600 thin sections over the course of my research and was really sick of that machine by the end. Not much time in the wet geochemistry lab, so I was spared the fumes and the smell of chemicals.

What has the experience of doing science been in the geoblogosphere? Have you bleed from wounds or blisters, or gagged on noxious fumes? Do tell! :-)

The practice of science has changed a lot off course since Joseph Priestley discovered oxygen. You can now spend a career in a clean silent lab. Just the hum of supercomputers crunching their way through gene sequences, or the silent hiss of a laser isotope or ion microprobe as it analyzes elemental distributions. I did that too (the microprobe part) and boy, was that a welcome break from that squealing thin section machine.

What has not changed is the recognition that science is an immensely empowering activity with the ability to transform one's outlook towards life. Certainly the giants of 1700's science, Joseph Priestley, Benjamin Franklin, Antoine Lavoisier amongst many recognized this just as surely and clearly as we recognize it today. They looked at science not just as an instrument that helped the industrial revolution chug along but as a weapon to further democratic ideals of justice and equality.

In my last post I quoted Joseph Priestley's thoughts on the role of science in society. Leaping ahead a couple of centuries here is another thought from a guy who knew a thing or two about science, Albert Einstein:

It stands to the everlasting credit of science that by acting on the human mind, it has overcome man's insecurity before himself and before nature.

There has been a lot of introspection and debate in India recently on how to build world class universities and how to attract bright people into pursuing a career in science in India as against going abroad. Those are extremely worthy goals. But to me the most important pursuit for any country is to produce a citizenry that has "overcome man's insecurity before himself and before nature". Abraham Pais, Einstein's friend and colleague called him "the freest man I have known". That is empowerment through science.

Not everyone can be a high-powered research scientist let alone be another Einstein. In fact the vast majority of educated people in any society will not spend a career practicing science. But if more and more are helped to inculcate a scientific outlook then that would be as good a step as any towards building a tolerant and just society. And that means giving equal importance to good quality science education at the high school and junior college level before people leave the sciences altogether and join different career streams.

See: My Book Shelf

Thursday, January 8, 2009

Drinking Coffee Triggered Britain's Age of Enlightenment

My Book Shelf- 5

I heard this tongue-in-cheek explanation for Britain's age of enlightenment and the Industrial Revolution in an engrossing talk on NPR's Science Friday. The guest Steven Johnson discusses his book The Invention of Air, a story of science, faith and revolution set in mid-late 1700's Britain. The talk centers around British scientist Joseph Priestley the discoverer of oxygen, and his friendship with the American founding fathers, Benjamin Franklin and Thomas Jefferson.

So what's the connection between coffee and enlightenment. It was in keeping the British population alert and away from alcohol. Since the water was rarely safe to drink, people turned to drinking alcohol since daybreak and were inebriated by mid-morning. The introduction of coffee broke this pattern. Caffeine made people alert but more importantly Steven Johnson argues that the coffee houses served as a meeting place for bright people from various disciplines to gather, discuss, strike business deals and dream up innovative ways of understanding how the world works.

I have this fat, beautiful book on my shelf; Jenny Uglow's The Lunar Men: Five Friends Whose Curiosity Changed the World, which elaborates this theme by detailing the cultural, economic and political landscape of 1700's Britain. Joseph Priestley was one of the five friends. Erasmus Darwin (Charles Darwin's grandfather), Matthew Boulton, James Watt and Josiah Wedgewood (Charles Darwin's maternal grandfather) were the other four.

And the five did meet often in coffee houses.

For in eighteenth century clubs are everywhere. Clubs for singing, clubs for drinking, clubs for farting; clubs of poets, and pudding-makers and politicians. One such gathering of like-minded men is the Lunar Society of Birmingham...

And on Britain's popular craze for science:

In exploring such matters Darwin and his friends were part of the great spread of interest in science that extended from the King and the Royal Society to country clergymen and cotton-spinners. When people talk of eighteenth century culture this is the swathe that is often missed out. the smart crowds thronging to electrical demonstrations; the squires fussing over rainfall gauges; the duchesses collecting shells and the boys making fire-balloons; the mothers teaching their children from the new encyclopedias with their marvelous engraved plates of strange animals and birds and plants.

Science was popular because it was 'gentlemanly' and cultured, and like all crazes it produced its share of jokes. But it was also a great spur to industry, helping Britain to surge ahead of other European nations.

So, an interest in science and innovation and their practical uses for industry was not restricted to eccentric scientists and industrialists. Britain's population across class and culture was largely a willing participant in this economic transformation.

In a way I found this paragraph anticipates the argument made by economist Gregory Clark in his book A Farewell to Alms, that the behavioral attributes of Britain's population had been changing toward greater industriousness for a few centuries before the Industrial Revolution. His theory is that over centuries disease killed of the poorer disproportionately. Their social position and trade was taken up by the literate and more productive sons of the wealthy, resulting in a population with a productivity rate that could break the Malthusian trap. This mechanism he has proposed - downward social mobility - is controversial. But whatever the reason, be it cultural evolution or genetic as Clark seems to favor, Britain's population was ripe and ready for enlightenment and the Industrial Revolution.

Coming back to the talk, it mostly focuses on Priestley's American connection, but it was his work and inventions in Britain in the company of the Lunar Society that Priestley is known for.

Amid fields and hills the Lunar men build factories, plan canals, make steam engines thunder. They discover new gases, new minerals and new medicines and propose unsettling new ideas. They create objects of beauty and poetry of bizarre allure.They sail on the crest of the new.

Amongst the five friends, Joseph Priestley was the true scientist and idealist. He believed that science and knowledge could be used as a weapon to further democratic ideals of political and personal freedom and equality among men.

He writes in his preface to Experiments and Observations in 1772:

The rapid progress of knowledge which like the progress of a wave of the sea, or of light from the sun, extends itself not in this way or that way only, but in all directions, will, I doubt not, be the means, under God, of extirpating all terror and prejudice, and of putting an end to all undue and usurped authority in the business of religion as well as science; and all the efforts of the interested friends of corrupt establishments of all kinds, will be ineffectual for their support in this enlightened age.

More than two centuries on, I find this way of thinking is still very much relevant.


See: My Book Shelf

Tuesday, January 6, 2009

India Space Org To Release a Google Earth Killer?

The Indian Space Research Organziation (ISRO) has announced that it will soon release a free online imaging service named Bhuvan (Earth) along the line of Google's two imaging services, Google Maps and Google Earth, but initially covering only the Indian subcontinent.

I missed this news until a friend pointed it out to me a few days ago. It appeared sometime in November and kind of coincided with the launch of India's first moon mission, the Chandrayan-I spacecraft.

Typical of an Indian government organization there is no news of the launch of this mapping service on the ISRO website. I guess they just want to surprise the world.

The Indian media in a swell of nationalistic pride after the successful launch of Chandrayan has dubbed this forthcoming online imaging service a potential Google Earth killer. I thought I would speculate a little on what kind of service ISRO might launch and whether it can compete with Google.

1) Will the images from Bhuvan be superior to that provided by Google?

The Indian media and the blogosphere thinks this is a battle of images and the service that will provide better images will win. I am skeptical, not just of the claim that better images is everything, but that Bhuvan will provide better images than Google.

Here are some snippets from the media:

Imagine if you could count the lions in Gir or fishermen find concentration of fish in the sea, just by dragging a mouse on a computer screen. Space Applications Center of ISRO has just made that possible by an innovation called Bhuvan.

If Google Earth shows details upto 200 metres distance and Wikimapia upto 50 metres, Bhuvan will show images upto 10 metres, which means you can easily see details upto a three floor high building and also add information.

It's clear that whoever has come up with this garbage has never been involved in satellite image analysis, nor has this person seen Google coverage of India recently.

One clarification. Google does not own the images you see in G Maps and G Earth. They license the images from DigitalGlobe who owns the imaging satellites, Quick Bird and World View. For the last several years Google has been providing very high resolution images of Indian cities and surrounds. Not the 200 meters or 50 meters resolution mentioned in various media reports but about one meter resolution. The rural areas are not high resolution yet. They are covered by a 20 meter resolution coverage from the imaging satellite SPOT.

Another claim of superiority of Bhuvan is that Google does not update its images for 4 years, while Bhuvan will provide a yearly update. Below is an Google Earth image of Belgaum, a provincial town in the state of Karnataka.


You can check the date of the coverage for a particular area in G Earth by looking under Layers- More- Digital Globe Coverage. Belgaum has a time stamp of July 2007. Other cities in India are also covered by recent images, bigger metros are covered by images just a few months old.

So Bhuvan is unlikely to compete with Google in image quality or in update cycles at least for urban areas. Bhuvan's main source of high resolution images will be the Cartosat satellite series, whose sensors have the similar capabilities as Quick Bird and World View. If ISRO takes a decision to cover rural areas also with high resolution imagery, then that would be an advantage over the currently available G image service. But faced with competition there is nothing stopping Google from doing the same.

2) Will ISRO make other data available?

The American comedian Bob Hope once quipped about London "Their clubs are so exclusive that even some of the members are not allowed in".

This is the kind of exclusivity that has marked access to Indian spatial data so far. The National Spatial Data Infrastructure, many years in the making keeps promising easy access to base data, but in reality getting hold of it is a tedious process. Check out the dysfunctional data search facility of the National Spatial Data Infrastructure Portal (also see map viewer, so slooooow...) , which is supposed to be the central data clearing portals.

If Bhuvan offer overlays of spatial base data, such as boundaries, roads, natural resources and other locally relevant data, then that will be a significant advantage over what Google is offering for India. Mind you this will not be actual spatial data you can download and manipulate in a GIS, but just images of the data. Even these would be useful information, especially if a query engine is included in the app. Let's see how much data is cleared for use in Bhuvan by the mandarins at the Ministry of Defence.

3) Will Bhuvan be like Google Maps or like Google Earth?

The media in dubbing this a Google Earth killer has not asked this simple question. There is a significant difference between the two G image services. Google Maps is a true online web mapping service. This means that the application resides on a remote server. Everything you see on your screen, the user interface and the imagery is being sent from that remote server to your computer. This makes the application slower, and so no wonder G Maps has a very simple interface.

Google Earth is a Globe, 3D spatial data viewer. It is not a true online mapping application. Yes you have to go online to use it, but only the imagery is being sent to you from a remote server. The rest of the application resides on your computer. That's why it is a 14 Mb download. Google wants to make sure that the complex user interface of G Earth which includes the globe and terrain and tilt viewing and the many options and tools work lightning fast. The best way to achieve this is to install it on your hard drive and access the functionality from there.

Here is a typical example
of a fairly complex user interface that is served out from a remote computer. Play around and then compare the speed of operations of the user interface with Google Earth and you will realize what I mean when I say that online mapping applications are slower than local applications.

No word from ISRO on what the software architecture is going to be like. I suspect it will be a true online application like G Maps. In that case ISRO needs to keep the interface light. Bandwidth is still not that great in India and a complex online user interface will slow the service and discourage users. So then Bhuvan will really be competing with Google Maps and not Google Earth. The attraction of the globe and 3D viewing in Google Earth will maintain its popularity.

4) Will ISRO allow open access to the Bhuvan API?

Maybe the make or break as far as popular usage of this service is concerned and for having any chance at all at eroding Google Maps popular user base. One of the reasons why Google Maps has become a phenomenon is that anyone can get a API key from Google and customize the application. It can be embedded in a third party website and you can add third party data and create mashups. This has lead to some very innovative uses of the service. Its usage has gone far beyond spatial mapping professionals.

Again this might be too radical a step for an Indian governmental organization to take.

In summary, Bhuvan no doubt will offer excellent quality imagery, but as I discussed not superior to Google. It's advantage may lie in offering additional spatial data layers. I am speculating that the service is likely to be used only by a small group of specialists and mapping professionals. I doubt if our government is ready to shed its control freak mindset and allow open access to API. This will limit not just the user base but also prevent creative use of imagery for myriad location based services that are so much in demand these days for urban and rural applications. That means it's unlikely to become as popular as Google Maps.

ISRO says they are going to launch sometime in March. This has been more of a speculative preview. I hope to give a more comprehensive review after launch.

If I get to hear of it that is.

Thursday, January 1, 2009

Allocyclicity vs Autocyclicity: An Old Debate Revisited

An old debate on sedimentary cycles and research topic choices came to mind.

Brian at Clastic Detritus has an informative post with some great images on the discovery of rhythmic sediments deposited on Mars. As the name implies rhythmic sediments are not just layered but a particular type of sediment has been deposited at a regular frequency throughout that geological section.

The origin of these rhythms is a widely researched area of stratigraphy and sedimentology. As Brian explained these rhythms or sedimentary cycles can be allocyclic in origin or autocyclic in origin. Allocyclic means that periodic changes in an external factor such as cyclic climatic changes forces the environments of deposition to change in a cyclic manner producing a cyclic sedimentary record. Autocylic means that the sedimentary processes within a sedimentary basin develop cyclic feedback loops linking sediment production, transportation and deposition. This results in similar environments of deposition appearing at and disappearing from any particular location within the basin at periodic intervals leading to a cyclic sedimentary record.

Preliminary work suggests that the Mars rhythmic sediments are likely allocylic in origin, maybe linked to cyclic climatic changes on Mars. Brian thinks they are chemical deposits formed in a large lake. Maybe; it will be fun following this research.

Coming back to planet Earth this debate on allocyclicity vs autocyclicity in carbonate strata was being played out in a big way during my graduate students days in the early-mid 90's. The focus of study was the Cambro-Ordovician passive margin platform carbonates of the central and southern Appalachians. Two big labs, one based in Virginia and the other in Tennessee developed quite opposing points of view.

At Virginia Polytechnic, J.F. Read headed the carbonate research group and championed the allocyclic model. All his students who worked on stratigraphy related projects found strong evidence of allocyclicity in the sequences they studied. Further south, Kenneth Walker of the University of Tennessee at Knoxville downplayed allocyclicity as a viable model for shallow platform carbonates and stressed internal feedback loops and autocyclicity as a better explanation for the observed facies changes. All his students found strong components of autocyclicity in the sequences they studied.

Mind you, the students from the two different labs were working on carbonate sequences from the same time period deposited in adjacent areas of the same tectono-sedimentary setting.

Even further south I worked on the Alabama and Georgia Appalachian carbonates for my thesis at Florida State Univ. I took the smart option. I avoided the debate altogether and worked on the geochemistry of cements.

But I did follow with interest the work of my colleagues up north. Both these founders of the two large research labs are influential charismatic personalities. I don't doubt that new eager graduate students imbibed a particular way of thinking about carbonate deposition by listening to their mentors. But why such a clear divide in research results?

I am in no way suggesting that students made up results to fit preconceived notions. Could it be that students were genuinely interpreting the same sequences differently because of a mental bias or simply due to an unclear understanding of the characteristics of these two different cycle modes. This may have happened in the very early days of the history of these research programs. But over the years stratigraphers have developed some pretty discriminating models of the two types of cycles. As the two research labs developed a more sophisticated understanding of the topic I suspect a more subtle bias developed.

Carbonate platforms vary in their water depth. There are really shallow areas, let's say just about knee deep water and there are areas which are few to several meters deep. It is in these slightly deeper water areas that signals of allocyclicity or external forcing are best preserved. Very shallow water areas, those in the intertidal and supratidal zone for example are more readily affected by internally produced disturbances and feedbacks in sediment deposition and production. These are areas where signals from externally forced cyclicity get swamped by locally produced cyclicity.

I didn't follow each and every thesis produced by these students, but what I am speculating is that students of Virginia Tech, started choosing as research topics slightly deeper water sequences which best made the case for allocyclicity, while students of Tennessee started choosing those environments of deposition where autocyclicity was the dominant process. The results they got may have been genuine but they were in a sense inevitable given their choice of a particular type of study material. I may be completely wrong but this is something you could test by a detailed literature review to see if there was a preference within the two labs for selecting particular environments of deposition to study.

Moving away from these carbonates to a more broader theme. How much does an influential mentor dictate the choice of your research project? I would be interested in hearing from other geobloggers. Did you have an experience of working in a large research lab with a larger than life research head, where a particular school of thought had been established and which influenced your work? Were you really critical of this established way of thinking or did you just accept it and use it as a foundation for your work?

Is it better then to choose to go to a smaller lab which might not have developed a tradition of thinking in any particular direction? And finally doesn't the influential mentor have a responsibility to develop internal differing points of view? How about assigning a couple of students on projects that might potentially disprove the established tradition?