Lord Rama's Bridge to Lanka - Part Deux

Last month, I published a post titled Lord Rama's Bridge to Lanka. In that post, I wondered as to how one can conclusively state that this bridge was man made, based merely on it's unique curvature. In response to Shastri's comment, I was curious if this bridge could have been formed due to wave action, over a long period of time. 

Phani Kumar, my friend and my class mate in the Department of Geophysics in Andhra University says that though it is a possibility in the Gulf of Cambay, it is impossible for wave action to produce sedimention in the waters between India and Sri Lanka. I provided complete explanation provided by Phani at the bottom of this blog post. I asked Phani if tectonics in the past 6,000 years or so could have caused this formation. He said that though it is a possibility, he hasn't heard of such a thing. 

Phani is the founder and CEO of a successful and well reputed geophysical Company in Mumbai. I respect his professional opinion. Based on his comments, I struck out the wave action from my list of possibilities for Rama's Bridge formation. 

The great news is, Phani's team has been working on Sethusamudram Shipping Canal Project* and his crew is conducting marine geophysical surveys along and across Rama's Bridge as we speak. What a great coincidence! Phani has graciously offered to share his knowledge on Rama's bridge, on receiving the data from his survey crew. He has also offered to provide us with photographs (if the bridge is visible) and scanned subsea morphological pictures. I find this very exciting. Please stay buckled at the edge of your seats until "Lord Rama's Bridge to Lanka - Part Tres" gets out of the oven! Of Course, the credit goes to Phani for offering to educate us on this matter.

An Excerpt from Phani's e-mail:

Regarding Rama's bridge ---- I quote here an excerpt from one of my reports on the surveys carried out in Gulf of Cambay, Off Hazira:

The Gulf of Cambay is bounded by the Saurashtra coast on the west and Gujarat coast on the east. The basement rock on either side dips steeply in the gulf as it forms a down thrust-side of the great “Western Fault” which runs along the west coast of India. The gulf is filled with younger sedimentary sequences.

Gulf of Cambay is subjected to 10 to 11 metres tidal variation with currents up to 8 knots. Many rivers viz., Narmada, Tapi, Mindhola, Purna, etc., flow into the Arabian Sea and meets the gulf on the eastern-side. Hence, the heads of the Gulf and the hinterland is infested with creek/estuarine systems. These river systems bring large quantities of sediments into the Gulf with every tidal cycle. In coastal area, tidal action creates intertidal flats and tidal channels. On intertidal flats, the tide rises and falls more or less tranquilly as a broad sheet of water. The deposition of sediments on intertidal flats is controlled by two mechanisms i) settling lag and ii) scour lag which are related to the mechanics of current in suspending particles and of picking-up of particles that have been deposited. Eventually, the particles were carried land/sea wards to a point where it becomes stranded on an intertidal flat before the ebb/flood tide gains enough speed to be able to erode it again. In tide channels, the flow is concentrated into swift currents. Coarser sand, skeletal debris, and other large particles remain as lag concentrates in the tidal channels. The survey area appears to near one such channel, the Sutherland. Hence, the sediments made available to the play an important role in keeping the gulf’s hydraulic and sedimentary regimes in a state of imbalance. This state is represented by the sediment transport, building of bars, forming of sand wave fields, establishing active erosional and accretional phases on different parts of the gulf.

The Gulf of Cambay is deep in its South part but much complicated in its north part by sandbanks, which shift under the influence of tidal bores and freshets borne down by the rivers. Major banks within the Gulf are Malacca banks, Eastern banks, Sutherland channel, Breaker banks, Narmada bank, Western bank etc. and these sandbanks are being subjected to greater changes in their shape position and elevations. Also very heavy shoaling is reported to have taken place in the entrance of the Gulf of Khambhat.

Hope you are not bored. Why I am quoting the above report is to let you know that sand bars, banks, shoals etc are formed in the Gulf of Cambay since it is subjected to 10 to 11 metres tidal variation with currents up to 8 knots keeping the hydraulic regime alive. In addition, many rivers bring-in large quantities of sediments. Where as off Rameshwaram where Rama's (Adam's) bridge exists, hardly any rivers flow into the sea and neither there is big tidal (maximum 1 metre tidal variation and 2 to 3 knots curremnts). Hence, there is NO WAY that a bridge can form naturally. Hope you are convinced now.

* ~Rs. 2,427-crore Sethusamudram Shipping Channel Project was inaugurated by Indian Prime Minister Dr. Manmohan Singh in June 2006.

Some what related quote:

A subtle thought that is in error may yet give rise to fruitful inquiry that can establish truths of great value. - Isaac Asimov