Thursday, December 23, 2010

Recommended Holiday Reading

A passage from Simon Winchester's Krakatoa, The Day the World Exploded: August 27, 1883 - early autumn morning in 1964, I was sitting in my room in the Sedgwick Museum in Cambridge.. when Toronto's Tuzo Wilson, on sabbatical leave, sauntered in clearly bursting to tell anyone who would listen about his new ideas. He had discovered that I was the new lecturer in structural geology and said: "Dewey, I have discovered a new class of fault." "Rubbish," I said, " we know about the geology and kinematics of every kind of fault known to mankind." Tuzo grinned, and produced  a simple colored folded paper version of his now famous ridge/transform/ridge model, and proceeded to open and close, open and close it with that wonderful smile on his face. I was transfixed both by the realization that I was seeing something profoundly new and important, and by the fact that I was talking to a very clever and original man.

Moments like these always enliven a science book and in Krakatoa there is a very satisfying section on the decades long accumulation of observations of gravity anomalies, remnant magnetism, volcanic island chains and faults and ideas on the earth's interior that culminated in the theory of plate tectonics. Tuzo Wilson's discovery that the sense of movement along faults that cut across mid-oceanic ridges is opposite to the then known transcurrent or strike slip faults on land was one such key moment. He had realized that such faults would form if  the ocean floor was somehow opening and pushing the split crust in opposite directions. Later observations vindicated his ideas.

Geology is not the only theme of this book. There is much to read about  colonial expansion and clashes of the Portuguese and the Dutch both between themselves and with the local Indonesian people. Geology, climate change, trade, cultural and religious evolution before and after the eruption are the narrative threads that Simon Winchester expertly weaves together.

I'm just one third through this book. Its great holiday reading.

I won't be posting now until early next year.. unless off course Anak Krakatoa.. the child of Krakatoa.. the new volcano that is growing at the rate of about 20 feet per year blows up..

Happy Holidays!

Thursday, December 16, 2010

Some Good Science Talks On Radio

A few terrific science talks I've heard recently:

1) A Biography of Cancer- Terry Gross of Fresh Air interviews oncologist Siddhartha Mukherjee.

2) The Man Who Killed Pluto - OnPointRadio's Tom Ashbrook talks to astronomer Mike Brown and astrophysicist Neil deGrasse Tyson about why Pluto has been relegated from the league of planets and some other frontiers of astrophysics.

3) Science Sees Further - Ira Flatow of Science Friday talks with Richard Holmes and Sir Martin Rees about the contribution of the Royal Society to science and its history and future.

Dissemination of scientific knowledge for improving public understanding of science with scientists playing the role of advocates and popularizers was a theme that Sir Martin Rees emphasized quite strongly in the talk.

Not long ago scientific societies did not always approve of scientists turned popularizers. Carl Sagan was infamously refused membership of the National Academy of Sciences, some say because of his public profile as a popular science writer and TV personality despite his excellent credentials as a research scientist.

The tide seems to be turning with scientific societies now actively engaging in science outreach in the number of ways.. take for example the recent meeting of the American Geophysical Union where a science blogging workshop and social media meetings are being held for exploring ways to strengthen the scientists connection to the public at large.

That is a good sign. Scientists should be talking more to the public about their work and its significance to society.

Tuesday, December 14, 2010

Remotely India # 3: Left Lateral Yamuna Fault

One of India's great rivers, the Yamuna, leaves the Himalayas and comes rushing on to the plains through a great tear in the Himalayan frontal ranges of the Siwalik mountains.

That breach in the mountains is a dislocation along the Yamuna fault. The sense of movement is left lateral, which means if you are following a rock formation across the fault, you will have to turn left as you cross the fault to trace the same rock formation.

Miocene onwards a thick wedge of fluvial sediments filled up a foreland basin that formed in front of rising thrust sheets uplifted along the active Main Boundary Thrust (MBT). That phase ended about 0.5 to 1 mya.

This fluvial wedge over the last half a million years has been deformed into the Siwalik mountains. These mountains form broad synclines and tight anticlines cut by north dipping thrust faults, a result of the continuing compression of the sediment wedge. The southernmost of these thrusts which brings into tectonic contact the anticlinal Frontal Range of the Siwaliks over the alluvial plains in called the Himalayan Frontal Thrust (HFT).

The HFT is broken into segments and the amount of displacement along these segments or thrust blocks is unequal. For example the blocks west of the Yamuna and east of the Ganga have moved southwards with an opposite sense of movement relative to the central block known as the Dun block. To view this, turn on labels and pan southeastwards in embeddable map below until the town of Haridwar where the Ganga enters the plains.

Thus the Yamuna fault has a left lateral sense of movement while the Ganga fault has a right lateral sense of movement. These faults can be thought of as lateral ramps of the HFT accommodating the displacement caused by the southwards movement of the HFT blocks. 

Structural considerations indicate that during the last 0.5 my there has been about 8 km of displacement along the Yamuna and Ganga faults, a slip rate of approx. 16 mm year.


View Larger Map

Saturday, December 11, 2010

A Map That Helped Abraham Lincoln

Disunion Blog has an interesting post by Susan Schulten on how a new map produced by the United States Coast Survey based on the 1860 census helped Lincoln and the public visualize the geography of slavery.

The map was produced with what at that time was a cartographic innovation.. the use of a shaded color ramp to represent ranges in values.. in this case the number of slaves per county in the southern states.


From the post:

The map reaffirmed the belief of many in the Union that secession was driven not by a notion of “state rights,” but by the defense of a labor system. A table at the lower edge of the map measured each state’s slave population, and contemporaries would have immediately noticed that this corresponded closely to the order of secession. South Carolina, which led the rebellion, was one of two states which enslaved a majority of its population, a fact starkly represented on the map.

The comment thread is interesting too... especially this argument.

Tuesday, December 7, 2010

Remotely India # 2: Dyke Swarms Of Northern Deccan Traps

Around Nandurbar in northern Maharashtra are spectacular outcrops of a dyke swarm intruding the Deccan volcanics.

Source: IRS-Resourcesat-1

 Models of Deccan volcanism envision that most the lava came out of vents and fissures localized along two major rift zones, the roughly east-west trending Narmada Tapi Satpura rift zone along which today the Narmada and Tapi rivers flow westwards and which initially developed in the Proterozoic but has been active intermittently since and the north-south trending West Coast rift zone which developed during the mid-late Cretaceous as India broke away from Madagascar around 90 mya. There are dyke clusters along these major rift zones and they are thought to be lava feeders, remnants of the pipes through which magma from deep magma chambers was brought up to the surface.

The dykes in the image belong to the Narmada rift zone cluster. They are mostly tholeiitic basalts in composition. Variations in chemical composition shows that the Deccan lava pile was built up through several major eruptive episodes. A comparison of this dyke cluster suggests that many of these dykes were likely feeders to the older and middle eruptive phases of the lave pile, although a feeder relationship with a lava flow is rarely seen in the field.


View Larger Map

Saturday, December 4, 2010

Friday, December 3, 2010

From Acid Mines To The Human Microbiome

Nature News has a fascinating article by Lizzie Buchen on human ecology... not the ecology outside and around us - but the ecology within - on which a variety of microbiota flourish.

That variety is now under scientists try to understand the linkages between the types of microbiota living inside us and our health. Establishing those linkages to the point where they could be of clinical value is a long way off but the efforts are bringing together unusual collaborations like the one where Jillian Banfield an expert on the microbiota of acid mines..the so called extremophiles.. is teaming up with Michael Morowitz and David Relman who are working on the microbiota in the intestines of premature infants.

...the connection...?

"The scientific questions are really cross-cutting," says Banfield. One example, she says, is colonization — which organisms arrive first and how the community evolves (see 'Baby's first bacteria'). "It's ecological succession," Banfield says. "If you look at the surface of a pool of acid mine drainage and imagine the first organisms to arrive, it's the same as imagining a newborn baby with a sterile GI tract, and the first organisms there." 

Plus, Dr. Banfield has experience sequencing and analyzing DNA from the microbes of acid mines where there are only a limited number of microorganisms. The infants intestine is similarly an ecosystem which has been recently colonized by only a few microbes, which makes it that much easier to categorize them using Dr. Banfield's techniques.

The article has a lot more on the emerging field of the human was an eye opener for me... in sheer number of cells we are 99% microbial...

how's that for a weekend thought..!

Thursday, December 2, 2010

United States Water Usage Maps Through Geocommons

Just a pointer that GeoCommons, a public domain web mapping application by Fortiusone Inc has a growing collection of geology and natural resources data.

I've been having fun last couple of days downloading some U.S. water use datasets, importing them in Manifold GIS, making them map ready and then uploading them back on Geocommons. Using the Map Maker I have then presented the results in a couple of maps.

The first shows the total ground water usage by state in millions of gallons per day (colored states) and also ground water use as percent of total water use (graduated dots). Orange blocks as urban centres with population greater than fifty thousand. You can see the east west divide in water use type. The east relies a lot more on surface water. The central and western areas along with Florida in the south east rely on ground water more than the eastern states. The importance of the Ogallala or High Plains Aquifer is clearly seen in the central states as is the importance of the Central Valley Aquifer in California.

View full map

You can drill down and bring out other dimensions of this data. For example in the map below I've plotted one of these dimensions, the ground water usage for irrigation in millions of gallons per day in the High Plains counties. The High Plains Aquifer is outlined.

View full map

This is not a full "cloud GIS" yet in terms of users borrowing or leasing the full range of GIS functionality from a remote computer. I had to follow a hybrid approach as did other data donors in terms of using a personal GIS to process the data to certain specifications before uploading it to this online service. Still such services are gaining importance and functionality and they give users who don't own software an inexpensive tool to actively engage with spatial data.