Hot earth

After reading about mudskippers yesterday, I eventually connected them with a bit of information I’d forgotten. In the time that mangrove forests and mudskippers were beginning to evolve on the western shores of the Tethys Ocean 50 million years ago, the earth went through a climate catastrophe. Geological eras have names that I find fascinating. This was the beginning of the Eocene epoch, the name means the dawn of modern times. If you want to be more specific, you might call it the Ypresian age, a 8 million year blink of time starting 56 million years ago. What I remembered was that in the Ypresian age the earth went through a heating event that we call the Paleocene-Eocene Thermal maximum (PETM). Temperatures across the earth were between 5 and 8 degress Celsius higher than it is today.

At this time the continents had not yet reached where they are today, as you can see in the map above, but they are not completely unrecognizable. The deep oceans saw a tremendous extinction; between a third and a half of ocean species died out. The oceans became acidified and hot. Their levels rose, water saturated the air. The poles warmed more than the rest of the world. As a result, the Antartic was forested and ice free, and tropical rain forests covered southern Germany. Canada, as far north as what is today Baffin Bay, had swampy conifer forests regularly ravaged by forest fires. The part of India which is now the Thar desert seemed to have had extreme rains and weathering during that time, whereas northern Spain was a parched desert. It is hard to prevent a large body from heating up, so mammals became smaller. This may have had many consequences, but one that has been followed up is that it encouraged a rapid evolution in the ancestors of today’s horses.

Although the map of this world looks almost the same as ours, this hot and rain-drenched world is not suited for agriculture. Estimates of our carbon future showed that in “business as usual” scenario we will be there by the end of the century: in the time of the grandchildren of the millennials. There is a reason that projections stop at the year 2100: no climate simulation remained believable beyond that. Very recently though, a climate model was able to reproduce the PETM using reliable estimates of the amount of CO2 then present in the atmosphere, by following the small-scale dynamics of clouds more accurately. This simulation seems to say that the future temperature rise could be more extreme than had been predicted. We live in unsettled times.

Filling a gap in history

The island continent of India drifted for 70 million years through the Tethys Ocean. It separated from Gondwanaland about 120 million years ago and collided with the Eurasian continent around 50 million years ago. 70 million years is enough time for large families of animals to evolve and die. So there must have been families which arose in the Indian landmass and migrated to the rest of the world later. The first such family has now been identified.

These are the Cambaytheres, a genus of fossil animals found at the bottom of an open-cast lignite mine outside of Surat in Gujarat. These 57 million years old fossils seem to be the origin from which all modern even-toed ungulates radiated out. These include horses and zebras, tapirs, as well as rhinoceros. The Cambaytheres were first described in an article published 6 years ago but I read about it only recently from a monograph published this year. The Cambay shale deposits have also yielded a very rich variety of other fossils from those times, and I’m sure we’ll be reading more about new finds from them.

The monograph has a very clear statement that although the genus is not the direct ancestor to any extant even-toed ungulate, it is the best possibility for the last common ancestor of all of them. Previous claims to the origins of this family are based on fragmentary fossil remains, or, sometimes, on conjectural remains. By the early years of the 21st century the possibility that the ancestors of horses originate in the Americas, Europe, and Africa had already begun to seem remote. A lot of attention then focused on new findings in China. Now, with a large collection of remains, from three species of this genus, much more can be said. Mysteries which remain are the routes through which the animals dispersed across the world, and then radiated into a large number of species in a few tens of thousands of years.

Cleopatra’s pool

The hot water of Pamukkale was gathered into indoor pools in antiquity. The story that Cleopatra swam in this pool cannot be verified, although you can now pay to relax in it. She is known to have visited Tarsus and Antioch, far to the east of Hierapolis, and Rome, very far to the west. I think it is unlikely that she took time off from survival politics to come to this place. Most tourists don’t care too much for this story either, and prefer the natural pools on the white cliffs (photo above). They are attracted more by the geothermally heated waters, ie, the geology, than the history.

For good reason. The deep geology of Anatolia is amazing and recent. Just after India, Italy, and Spain collided with the newly forming Eurasian continent and pushed up the Himalayas, Alps, and the Pyrenees, the Tethys seaway was a continuous strip of sea that joined the Mediterranean to the Indian ocean. Between 20 and 10 million years ago, Africa and Arabia pushed north to cut off the Tethys sea.

As a result, the sea bed was pushed above the Eurasian continental plate, forming the Anatolian plateau. The Aral, the Black, and the Caspian seas are the last remnants of Tethys. The closing of the Tethys sea also created the major temperature fluctuations of the last 20 millions years or so, causing huge extinctions, and clearing the way for the rise of modern day mammals and birds. The continuing northward movement of Arabia, and the southwestern movement of the Aegean sea bottom still squeezes Anatolia, making this one of the most geologically active regions on the globe.

This activity not only pushed up the plateau on which ancient Hierapolis stood, but also created the fissures, called faults, which run through it. The raising of the plateau creates a cliff which faces the modern village of Pamukkale, Rain water and snow seep through the crust, are heated underground, and emerge again at various places on the plateau to form these hot springs. The waters are loaded with minerals of various kinds which deposit as the water cools. The flow of water down the cliff has formed these immense terraces of limestone called Travertine.

I’d only seen photos of white Travertine terraces, filled with pools of water. But actually there are various colours to be seen. This is natural, since the water coming out of the earth must have more than just lime in it. These other minerals give the limestone its colour. You can also see in these photos the interesting variety of textures in these deposits. I waited till a little before sunset to take these photos. Then, as the air cooled, The Family and I found our way out of the plateau through the south gate, and came down to the village.

Memories of Phobjika valley

The six of us struck off eastwards across Bhutan with no particular destination in mind. We had a vague idea that we would stay one night each in a valley. Phobjika valley was the first we came to. We made a turn off the forested east-west road, and drove for a little more than an hour until the forest opened up very suddenly. In front of us was a wide valley carpeted in green (featured photo). We took a second look, because the carpet of greenery was not grass. It was a stiff ankle-high plant, which was very hard to push through. We decided not to climb the first hills we saw, but to go on ahead.

In 2008 Bhutan was still in its last year as an absolute monarchy. You could not book hotels outside the Thimphu-Punakha-Paro triangle on the web. We knew that some tourists came to Phobjika, so we were pretty certain that we would find a few rooms. We drove along the road, and soon came to a little village. There was a family-run hotel, and they had rooms.

People in Bhutan are extremely friendly and informal. We gathered in a little dining room with the family. A baby was handed to us, and as we kept him entertained the table filled up with snacks. There was a mixture of dishes made with local produce, and simple packaged things like biscuits and tea. The long transport lines needed to bring them here made them extremely expensive. Dinner included a wonderful thukpa made with vegetables freshly plucked from the garden.

Layers of blankets and a wood-burning radiator in the middle of the room kept us warm through the night. Phobjika lies between 2900 and 3200 meters in altitude, but in the middle of May temperatures could dip down to 4 Celsius at night. In winter there is enough snow that some villagers move away to more comfortable valleys.

The next morning after breakfast The Family and the rest went off bird watching. I decided to take a walk down the valley. Bhutan is built from material laid down half a billion years ago near the Tethys Sea, and carried here by the Indian continental plate. The geological events that made Bhutan occurred mainly in the last 20 million years, and have been mapped extensively by the Geological Surveys of Bhutan and India. As the Indian plate pushes up the Tibetan plate, the sheets of ancient rock concertinaed and folded vertically along the east-west axis we were traversing. As a result the Tethys rocks metamorphosed into the minerals seen here today.

The gently sloping Phobjika valley lies over white granite rocks distinct from the geology of Paro to the west and Bumthang to the east. Glaciation in the last few thousand years may have initially started the valley. However, its present form is due to the action of monsoon, repeated frosts and snowfall, and the wind that constantly blows across the valley, carrying topsoil with it. Interestingly, there is evidence of pre-historic human slash-and-burn agriculture in the last two thousand years in the form of deeply buried charcoal. This ancient abuse is perhaps what cleared the valley of the forest cover which lies around it, and caused the soil to turn unproductive. I wonder whether the two rivers which wind through the valley today, the Nake Chu and the Gay Chu, flowed in those days.

I walked along an unpaved road with the valley sloping away to my left. The weather was mild enough, even with the breeze that brought clouds tumbling over the far hills. Along ridges I could see rows of flags: white for mourning and coloured for prayers. The Buddhist belief here is that the winds blow these prayers and distribute them over the valley.

The poor soil needs prayers. As I walked along, I noticed the rocky ground with a thin covering of red dust. Hardy wild plants straggled across it, and strange insects scuttled between patches of growth. Ferns grew out of the soil, hiding spiders in their spiral folds. In the distance I saw farmers at work. Once I passed a cow which turned to follow me with her eyes without interrupting her mouth.

A truck drove by and the friendly young driver leaned out to smile and wave. A young child scuttled away from me and then gathered enough courage to peer at me from around his door. The mother came out to investigate, and gave me a friendly wave. After a while I saw school children walking back home. This gang of four planted themselves in front of me and told me in their broken English to take a photo. They stood grim-faced for the photo, but immediately after that broke into smiles and started pushing each other. It was time for me to get back for lunch and find out which birds The Family had spotted.