Ram Sethu : A Dummies Guide

By now everyone has had saturation coverage of this issue. For those still uninitiated, Ram Sethu refers to a hypothetical man-made causeway bridging the Palk Strait between India and Sri Lanka. Because it is believed to have been built by Sri Ram on his way to Sri Lanka, a recent report by the Archaeological Survey of India, stating that the Ram Sethu is a natural formation and that there is no scientific evidence of the existence of Ram has ignited a controversy. Sensing a popular backlash, the government in an act of gross cowardice have censored the scientists, whose job was to present scientific evidence and which they did. These issues have been dealt with here and here. Since my interest is in science I will write about that. I have watched with increasing disbelief over the gross ignorance shown by media and various "experts" over the validity, reliability and appropriateness of the different scientific tools that are being used to assess the status of Ram Sethu. So I have compiled a dummies guide to Ram Sethu, which points out the various misunderstandings and misinterpretations of scientific techniques and data.

1a) Satellite images clearly show natural formations of sand shoals and coral islands. Therefore the Ram Sethu is a natural formation. 1b) Satellite images show a continuous linear feature connecting India and Sri Lanka. Therefore the Ram Sethu is man-made.

Both conclusions drawn on the basis of satellite data are wrong. 1a) The satellite image do show natural sand shoals and coral islands. But the images being used to draw this conclusion cannot resolve features that lie on the sea bed. There could well be artificial structures that cannot be seen in the images. 1b) The continuity of the linear feature seen in the satellite images is an illusion caused by suspension of calcium carbonate sediment and cloud cover. Seen from great altitude this appears to be continuous. Close up of the Palk Strait show a discontinuous series of islands. In short, the commonly shown satellite images due to their poor spatial resolution and their inability to penetrate through water (spectral resolution) cannot be used to make any inferences about what lies on the sea-bed.

2a) NASA scientists say that Ram Sethu is a natural feature. 2b) NASA scientists have left the question open to interpretation, so there could be an artificial struture.

NASA scientists have never been to the Palk Strait and looked at the undersea geology themselves. Why this obsession with NASA scientists? Why not discuss geological research done by Indian scientists, who have actually done field work in the Palk Strait.

3) The Ram Sethu is millions of years old. So there cannot be an artificial structure in the Palk Strait.

Again a wrong conclusion from a partially correct statement. The rock formations and sediments in the Palk Strait were deposited over millions of years at least from the Miocene to the present. No matter how old some the rocks are, there still could have been a recent construction of some sort, using these old rocks as building material.

4) The sand in the Palk strait is just 3500 years old. This supports the idea that the Ram Sethu was constructed by Sri Ram.

Wrong conclusion from possibly correct data. Many of the sand shoals are of Holocene age. But this is unconsolidated sand, which has been brought in by currents from the southern Tamil Nadu and Jaffna coastlines to form natural sand islands. The correlation of age between these sands and the purported age of the Ramayan is purely coincidental.

5) Carbon dating has shown the Ram Sethu to be a lakh or few lakh years old.

Carbon dating uses the amount and natural decay rate of C14, an isotope of carbon to calculate the date of artifacts and other organic materials. It cannot be used to date organic materials older than around 40 thousand years. This is because the half life of C14 (time required for the quantity to decay to half of its initial value) is about 5700 years, and in about 8 half-lives the amount of C14 left in the material is too little to measure accurately.

6) Geological cores have shown the presence of boulders on top of sand in the vicinity of coral islands in the Palk Strait. The boulders could not have appeared on top of sands by any natural process. So they are man-made features, part of an ancient causeway.

Again an astonishingly ignorant statement by a senior geologist. I have posted a detailed criticism of this, describing how natural processes can easily explain the presence of boulders on the sea floor.

7) Some of boulders of coral rock are light enough to have floated on the water.

As ignorant as it gets. What pray tell us , then are the boulders doing on the sea-floor? Coral rock is made up of calcite and aragonite, minerals with a specific gravity of 2.71, much more than water.

8) The causeway was built during a period of sea-level fall a few thousand years ago when much of the Palk strait sea bed was exposed.

Again not possible. Holocene sea-level falls as shown by coral reef terraces (bands of corals growing at different heights) were not big enough to have lowered sea-level to any appreciable extent.

9) The Ramayan is 1.7 million years old.
An absurd statement. Humans did not exist at that time. I will not dwell on this, as it has been covered by this excellent blog.

10) The Ramayan is 9000 B.C, 7000 B.C, 5000 B.C. take your pick.

I listen and read in amazement when dates are thrown recklessly and with full confidence by historians and scientists alike (Time of India Sept. 14 '07 quoted eminent anthropologists given dates as old as 5000-6000 B.C.) without a murmur of dissent or criticism by our media. All these dates are too old. All three dates take us back to the stone age. The metal age in the Indian subcontinent began around 4000-3500 B.C. The Ramayan judging by the descriptions takes place in the iron age, which began in the Indian subcontinent around 1800-1500 B.C. The totality of the archaeological and linguistic evidence suggest that the Gangetic plain societies which the Ramayan describes arose starting around 1000 B.C.

I have observed in particular the careless use of dates to support either the natural formation or man-made point of view. As I have described above the dates of the rocks and sediments do not by themselves inform us on whether there is an artificial causeway. But there are two types of information about dates of the rocks that are extremely important, the significance of which have escaped the media and scientists alike. The first is the dates of the coral terraces at Rameshwaram island. The oldest coral terrace is about 5400 years old. The second terrace about 10-15 cms below is about 3900 years old. Some distance away at Mandapam the upper terrace shows an age of 3600 years ago and just 20 cm below that one gives an age of 2630 yrs. Do coral terraces reflect oscillations of sea level or do they simply reflect that loci of coral growth shifted over time due to local changes in water quality, sediment disturbance and nutrient availability? As yet there does not seem to be field evidence that shows exposure surfaces between these terraces which would be an indicator that sea-level fell, exposed large areas and then rose and drowned the area again, forming the younger terraces. Such an exposure surface will provide a reliable data to the sea -level fall. At present all we can say with any confidence is that sea -level fell after 2600 years B.P. Holocene sea-level fluctuations did take place but they were likely not extensive enough to expose the Palk Strait sea bed over most of the basin as happened in the Pleistocene. The second situation regarding dates is hypothetical but presents an interesting situation. Suppose an artificial structure is found on the sea floor, but the dates of the boulders indicate that the boulders are just few hundred years old. What would supporters of Ram's bridge say then?

If readers have any other nuggets of inane statements by media and experts please let me know and I will write another installment.