The geology of paradise

Ritchie’s archipelago lies a little east of Port Blair. This group of islands includes Havelock and Neil Islands, often considered to have some of the best beaches in the world. The white sand beaches, the clear water and the warm sunshine seem appropriate to the quiet lifestyle of the locals. I could imagine myself settling down to months of slow life here.

Coral boneyard, Laxmanpur beach, Neil Island, Andaman

Walking along the soft sand one occasionally comes across patches of rubble like the one you see in the photo above. They are pieces of broken coral, the bones of the sea, piled up in these little boneyards. When I saw them I began to wonder about the geological processes which form these little bits of paradise. Although coral reefs are spread across the world, their total area is about that of the state of Maharashtra. In terms of area, this is one part in a thousand of the world’s oceans, but it contains a fourth of all ocean life!

Rocks on Sitapur beach, Neil Island, Andaman

Our understanding of coral islands such as Neil and Havelock comes from Darwin, the master of careful scrutiny and understanding. He figured that such islands are volcanic. In the shallows around these new islands corals begin to accumulate. As the volcanic cone subsides, the corals grow upwards and outwards in the shallow waters.Corals around Neil Island, Andaman If their upward growth keeps pace with the sinking of the island, then eventually they form the wonderful reefs we saw around the islands (there is a brain coral at the bottom of the photo on the right). Too slow, and they would become drowned reefs. The volcanic rocks which supported the initial growth are also visible around these islands, as you can see in the photo above. The coral reef system is young, only about ten thousand years old.

Dead coral, Bharatpur beach, Neil Island, Andaman

The Andaman islands have been through a geological catastrophe about a decade ago. The 2004 Indian Ocean earthquake which generated a devastating tsunami was centred near these islands. You can see its devastating effects on the coral ecosystem even today. The sea bed rose by almost a meter, popping a large area of corals above the water and killing them. The great diversity that one sees in scuba dives off the coast of these islands is a fraction of what was there even as recently as 2001. Coral reefs are also sensitive to a variety of easily avoidable man-made perturbations: dumping of untreated organic waste such as sewage and chemicals from agricultural runoffs and even sunscreen. A little awareness for the next few decades would be enough to let this ecosystem recover.

Across the Bay of Bengal

Ten days after cyclone Vardah travelled from the Andaman Sea over the Bay of Bengal to hit Chennai, we flew backwards along its track. The sky over Chennai was a clear blue. As the plane nosed up,Ocean and sky after a cyclone I saw a few banks of fluffy clouds near the horizon. The sky below us was clear as our Airbus 320 reached cruising height. The flight to the Andaman archipelago would take almost two hours. The sky below me seemed clear; only a few stray fluffy clouds occasionally interrupted my view of the calm seas. But when I looked up, there was a thin layer of cirrus clouds very far above the cruising altitude of the plane. They looked dark against the otherwise clear sky. You can see them in the upper half of this photo. You can also see a few wisps of white cumulus clouds against the blue of the sea in the lower part of the photo.

A coral atoll around one of the Andaman islands

The monotony of flying over the ocean was just beginning to lull me to sleep when the plane began its descent. As we came in over the outlying islands, cloud banks piled up ahead of us. The air was not as clear as it had been before. I realized later that clouds tended to mass up near the islands and coast in this season. As a result, the image of the coral atoll surrounding the island in the photo above was hazy, and I had to tweak the photo quite a bit to see the beautiful patterns in the water around the island. It was lovely to see the surf breaking far from the white sandy beach around the island.

The descent to Port Blair was fast, and I barely clicked a few more photos as we came lower. Almost the last photo I managed to take was a beach surrounded by corals. This is the featured photo. The water is so clear that you can see the coral reefs and the wide tongue of white sandy beach. I knew we were in for a great holiday.

Checklists

One part of going to the Andamans is to spend time in the water and beaches. Another part is to walk through forests and swamplands looking for birds and local animals. Meaning to look for checklists of birds, I searched for “checklists” instead. The results surprised me.

There are more than ten kinds of birds which are endemic to this island group, and are found no where else. This includes four kinds of owls! The one species that I’ve had my metaphorical sights on is the Narcondam Hornbill. But I think this is also the one I won’t get to see, given than a trip to Narcondam Island, 262 Kms from Port Blair cannot be accomplished between sunrise and sunset. Since we have already ruled out the long side trip to the Nicobar archipelago, we will also miss seeing the Nicobar Megapode, and the endemic Nicobar species. Still, that leaves us with many hours tramping around the wilds.

Where there are birds there must be snakes. There is a list of more than twenty, including some venomous sea snakes and even a Krait and Cobra endemic to the islands. These are creatures I would not like to run into.

A great checklist was of marine molluscs. Unknown to the public at large, the Zoological Survey of India continues to do its slow job of collecting and documenting life in and around India. The booklet by Ramakrishna and Sen says that " they are more diverse and abundant in the rocky intertidal zone along the coast and in the inter-tidal area of … the Andaman and Nicobar Islands" So I think walks along the beach will show us shells we have never seen before.

Nudibranch, opisthobranch (look at the wonderful description of the pink sea slug in the featured image!) and polychaetes are two groups of marine molluscs which I might get to see on a dive, provided I’m not too busy staying oriented. The paper I’ve linked above shows animals with wonderful colouring. I wonder how much of the colour is visible underwater through goggles. Since I’ve never dived before, I think I’ll probably spend a lot of time thrashing around. I’ll be lucky to see any of these.

There is even a checklist of the mosquitos of the Andamans. Of the 3541 species of mosquitos recorded from around the world, in 112 genera, these islands contain 109 species in 25 genera. More than a fourth of all mosquito species in India can be found in these islands. That’s something to remember when I forget my anti-mosquito gel.