BIRTH OF BALOCHISTAN

[Zahida Raees Raji]

BIRTH OF BALOCHISTAN
Mahmood Siddiqui & Uzma Mahmood
 
UNTO DEATH SHALL US PART
 
It would be fascinating to know that Balochistan, the land of such immortal love stories as Sassi-Punu, Hani-Shah Mureed, Sammo-Mast and Graanaz-Peruk, itself is the outcome of a romantic union between two discrete pieces of Earth. If the ancient people had known this fact, they would have woven a story like this: “Long long ago the god of Frozen Land of South Pole, where Sun seldom rose above the horizon, met the goddess of the land of Ever Sunshine, which existed across the ocean on the southern coast of Eurasia. The god was so enchanted with the heavenly beauty of the goddess that he fell in love with her. The goddess though liked the god of Frozen Land but was reluctant to leave her Ever Sunshine soil and be wed off to live on a frozen land. She placed a condition that she would marry the god only if he could prove the strength of his love by bringing his empire next to her warm and sunny country. The god agreed to the condition and on reaching back to his kingdom, abdicated his throne, tore a chunk of land from his enormous empire, and riding that piece of land started his journey across the ocean. The piece of land, due to its heavy weight sailed at a pace of toe-nail growth, and it took the god millions of years to reach the other end of the ocean. On reaching the coast of Eurasia he found that the land in immediate neighbourhood of his love was captured by another suitor of the goddess.  The god felt so jealous that he pushed the rival’s territory away and made room for his land to get permanently anchored by the side of his beloved’s soil. The two lived happily thereafter.”
Today the territory of the native goddess is known as western Balochistan and that of vagabond god as the eastern Balochistan. As a testament of their eternal love the two pieces of land have merged together into a single geographical unit — the present day Balochistan.
Balochistan was created millions of years before birth of mankind, leaving behind little telltale clues. Therefore, no such mythology exists in our folklores. Natural processes nevertheless can at times be more amusing than fairytales. Modern science indeed tells us that Balochistan was created by merger of two entirely different land pieces. It however replaces the fictional god and goddess of the story by the concept of continental drift and ocean floor spreading1. In fact, almost entire world has been tailored this way through attachments and detachments of fragments of the continental crust. To get a deeper insight of this “hard to believe phenomenon” we may peek into the geological past.

RESTLESS CONTINENTS

Continents are ceaselessly moving on the face of Earth. Evidence of their movement can be traced as far back in past as Proterozoic (geological time scale ranging from 2700 to 600 Ma. ago. (Ma = million years). While moving they assembled and coalesced together several times in the past only to breakup and disperse again. It was during Permian (295-250 Ma ago) when they lasted united into one.  Even today the process is reshaping the map at several places on the Earth. For instance, Arabian and African plates lay side by side in the past. Movement of the two plates in opposite directions created a rift between the two land masses which was filled by the Red Sea. Since the two plates are still moving in different directions, it can be predicted that in due course of time, say after a few million years from now, Red Sea will be widened and Africa will gradually move farther away from Saudi Arabia.
 
ONE OCEAN ONE CONTINENT WORLD

Sir Francis Bacon, an English philosopher, was among the first to observe in year 1620 that the outlines of the continents on a map can fit into one another in an incredibly precise way. For instance, costal outline of southwestern Africa perfectly conforms to the eastern coast of South America.  Bacon, however, could not put forth reasons as to why it was so. About 300 years later, a German meteorologist and physicist, Alfred Wegener (1880–1930), took Bacon’s observation a step forward. He concluded that all the continents are pieces of a super continent Pangaea (Greek: all land) that existed in ancient times in the centre of a worldwide ocean Panthalassa (all sea; named after Greek goddess of sea) (Figure 3-1 A). Pangaea is commonly believed to have formed sometime between 280 and 260 Ma ago during Permian, when all the landmasses annexed together to constitute this single super continent.
Pangaea, according to Wegener, subsequently broke to pieces that drifted apart to produce the existing seven continents in their present configuration. For this reason, he argued, outline of the continents could be placed together, like pieces of a jigsaw puzzle, to reconstruct Pangaea as it was prior to its break. And, for this very reason animal and plant fossils and rock formations now found in widely separated regions, are similar to those found on the corresponding edges of different continents. 
 We now know that Trans Atlantic communication cables sometimes give way due to excessive stretch caused by drifting of in between tectonic plates in different directions. In those days, the hypothesis of ocean floor spreading and continental drifting was yet to be discovered and at that time nobody was prepared to believe the notion that huge continents could move. On the premise that if the continents ever moved they must have left behind drag marks, the ocean floors were scanned for evidence, but in vain. No drag marks could ever be found. Despite of his firm belief on his continental break and drift hypothesis, Wegener could not present mechanisms strong enough to satisfy his contemporary scientists. In pursuit of yet stronger evidence to prove validity of his hypothesis, he finally traveled to Green land ice cap where he lost his life for the cause of science.
After his demise, Wegener’s brainchild of continental break and drift was soon put a side. Though during his life he could not prove his hypothesis, Wegener still deserves credit for being the first philosopher / scientist who advanced hypothesis of the continental drift — the forerunner of modern theory of plate tectonics.
 
PANGAEA SPLITS INTO TWO  

            Radiometric dating of rocks of Permian to Early Jurassic (295–180 Ma), according to Press and Siever (2002), suggest that break-up of Pangaea began about 200 Ma. ago in Early Jurassic. The split began along a wedge-shaped sea called Tethys that extended from Panthalassa westward into Pangaea (Figure 3-1 A & B). Two extra large continental landmasses, Laurasia in north and Gondwanaland in south, resulted following the break (Figure 3-1 B). Soon after creation, the two newborn continents began drifting; Laurasia moved northwards and Gondwanaland towards south and the movement of the two landmasses in opposite directions widened the in between Tethys Sea.

Figure 3-1 Pangaea intact (A) and after break (B)(Source: Press and Siever, 2002).

[Zahida Raees Raji]

MYSTERIOUS CONNECTIONS
 
            People of India and Pakistan find a bit of emotional attachment with the term “Gondwana”. Now so well known world over, the term was initially coined in the subcontinent in context of continental rock formations about 140 years ago. According to Krishnan (1958), Medlicott was first to use the term in 1872 in an unpublished report for the sedimentary beds he observed in Madhya Pradesh, India. The name presumably was derived from the ancient Gond Kingdom south of River Narmada, where these strata were first studied. Feistmantel, used the term in a paper published in 1876 in Records of the Geological Survey of India, volume IX (part2, page 28).
            Subsequent exploration in widely apart regions of the world, such as South Africa, Madagascar, Australia, Antarctica and South America etc., revealed presence of continental formations and collections of fauna and flora identical to those found in the subcontinent. Term “Gondwanaland” accordingly, was extended to include all such regions in other parts of the globe where Gondwana-like features were observed. To validate an unbroken chain of faunal and floral evolution in regions that were widely separated by oceans, land connections were essential. Accordingly, several fictitious connections were proposed and debated. For instance, imaginary land bridges extending from South America to Australia and Antarctica to Malaysian Archipelago through India were suggested. Even existence of a fictional continent, which was assumed to have existed in past and later sunk in Indian Ocean, was also proposed.
            Gondwanaland concept, since it proposal over hundred years ago till the advent of theory of plate tectonics in seventies of the last century, therefore, was nothing more than a vague and misty contemplation. As the Theory of Plate Tectonic2 up-held long distance movement of the tectonic plates, the concept of drifting of continents remained no more inconceivable! Movement of continents, as we now know, does not take place on ocean floor; it occur over soft and partly molten asthenosphere at a depth of 100–250 km below the Earth’s surface. Fantasy of imaginary land bridges or that of the disappearing continent are thus no more required to justify land connections in between the far away regions. Breaking of Gondwanaland is believed to have produced fragments of the Gondwanian crust that dispersed to distal places along with the groups of continental rock formations and plant and animal collections. Wegener had explained his observation of conformity of the outline of continents and similarity of the inhibiting living beings in these words, “It is just as if we were to fit the torn pieces of a newspaper by matching their edges and then check whether the lines of print run smoothly across. If they do, there is nothing left but to conclude that pieces were in fact joined this way.” The theory of plate tectonics has now made it possible to trace the history of origin of the continental pieces and reconstruct their voyage track in the geological past. The rationale of regions lying thousands of kilometer apart and yet having identical rock bed and fauna and flora is thus no more a mystery.
 
OUR PART OF WORLD ON THE GLOBE   

Gondwanaland after creation, according to Powell (1979), remained intact up to Middle Jurassic (180–160 Ma ago). Thereafter it rifted apart to constitute landmasses of Arabia, Africa, Madagascar, South America, Sri Lanka, Indo-Pak subcontinent, Australia, New Zealand and Antarctica (Figure 3-2). Except South America, which drifted farthest away in the west, the remaining pieces of the Gondwanian crust did not disperse far apart and constituted our part of the world. All these land pieces except Arabia and Africa with Madagascar are believed to have moved from their original positions and relative to each other. Arabia, however, according to Powell (1979), did not move but has rotated about 6.5o anticlockwise relative to Africa.

http://baask.com/articals/sangat/birth_of_balochistan/image004.jpg



Figure 3-2. Rifting of Gondawanland produced
most of today’s continents. (Source: Powell, 1979).
 
THE PLATE THAT TRANSPORTED
EASTERN BALOCHISTAN
Indian-Australian plate, a composite lithospheric3 unit, is built of both continental and oceanic lithospheres. It developed due to coalescence of two sizeable fragments of Gondwanaland to a large piece of oceanic crust. To the northern end of the plate is annexed the Indo-Pak subcontinent and to the southern end is attached Australia and New Zealand. South of Australia the oceanic plate extends further south till it comes in contact with oceanic portion of the Antarctic plate (Figure 3-3). In fact to the north of India also existed a portion of oceanic crust that was subsequently subducted4 under Eurasia leaving behind its relicts in Indus Ophiolite Belt in Ladakh in the Himalayas.   


Figure 3-3 Eurasian, Arabian, African and Indian-Australian
tectonic plates constitute the eastern group of continents in
east of the Mid-Atlantic ridge. (Source: Chernicoff, 1999).

OUR CORNER OF THE PLATE  

Indo-Pak subcontinent up to the eastern Balochistan occupies the northwestern portion of Indian-Australian plate. This portion of the plate, accordingly, is named as Indo-Pakistani lithospheric plate. Lower part of the plate (the basement) is built of Precambrian (older than 600 million years) metamorphic rocks of Gondwanian affinity and is called Gondwanian shield. Term shield refers to a large region of Precambrian rocks that is resistant to folding and normal faulting5. The shield in Pakistan, except in small part of Sindh and Punjab, is buried under thick pile of younger rock formations. Where exposed, the Gondwanian shield is called Precambrian Indo-Pakistani Shield or simply Indo-Pakistani Shield. The shield though extends under upper crust  up to Chaman fault in Balochistan, it does not expose itself  in the province.
 
VOYAGE OF EASTERN
BALOCHISTAN IN TETHYS OCEAN

Following its creation in middle Jurassic (~170 Ma ago), Indo-Pakistani continental plate started northerly voyage in the Tethys Ocean towards Eurasia. Eurasia was a continent that formed by breaking of Laurasia, the twin sister of Gondwanaland. Powell (1979), in a sketch diagram, shows some stages of the drift. (Figure 3-5). Starting 130 Ma ago, Indo-Pak subcontinent along with eastern Balochistan, moved northwest relative to Australia and Antarctica at the rate of 3 to 5 cm per year and reached east of Madagascar 80 Ma ago. Since then to about 53 Ma ago the subcontinent moved rapidly at an average speed of over 15 cm per year. Finally, from 53 Ma ago to present the Indian-Australian plate is moving as a single unit at the rate of 4 to 6 cm per year. During this last stage the plate, according to Powell (1979), has also rotated about 20o counter clockwise. As eastern Balochistan is part of the plate it also traveled along with rest of Indo-Pak subcontinent. The plate in fact is still moving northwards and indenting into Eurasia at its northern edge.


Figure 3-4. Some stages of the drift of the Indo-Pak
Subcontinent in Tethys Sea. (Source: Powell, 1979).

[Zahida Raees Raji]

DID CHITRAL ONCE LIE BY
WESTERN BALOCHISTAN?

            Unlike collision of two automobiles, continent to continent collision does not occur as a sudden impact. Slow drift velocity but enormous momentum of tectonic plates due to its huge mass, makes motion of the plates slow but persistent. Collision of the Indo-Pakistani continental plate against Eurasia, accordingly, did not occur in a moment and after the initial contact it took the subcontinent millions of years to come in full contact with Eurasia. The collision, according to Powell (1979), began in Early Eocene (~57 Ma ago) by initial contact of the Indo-Pakistani plate with an island arc or continental margin that then existed at the southern end of Eurasia. The full contact took place at least 33 Ma later, during Miocene (25–5 Ma ago) and the northerly push of the subcontinent continues even today. As a result, Indo-Pak subcontinent has been forced into the mainland Eurasia for considerable distance. Chitral at the time of first contact was located in the southern part of Eurasia, to the east of present day western Balochistan. The region was pushed northward into mainland Eurasia and today the region is over 1000 km away of its position prior to the collision. Its place since then has been taken-up by the crust of eastern Balochistan and Sindh that reached to the present positions along with rest of the subcontinent. In a nutshell, present day Balochistan was formed when eastern Balochistan which is Gondwanian in origin, annexed itself to western Balochistan that existed in the southern part of Eurasia, a piece of Laurasia.
            Collision of the Indo-Pak subcontinent against Eurasia was certainly the most significant event in geological history of the region. It has played extremely significant role and has cast profound effect in sculpturing the subcontinents geomorphology, controlling its topography, setting trend of its mountain ranges and watercourses, and finally carving the present-day portrait of Indo-Pak subcontinent and the adjoining region.
 

RISING OF THE HIMALAYAS 

 

The name Himalaya comes from the Sanskrit words, hima, meaning “snow,” and alaya, meaning “home”, so the Himalayas are home of snow. The snow capped Himalayas are the highest mountain ranges on the planet that house the world’s tallest peak Mount Everest (8850 m) in Nepal and the second highest summit K2 (8611 m) in Pakistan. This enormous mountain range was created as a result of collision of Indo-Pakistani plate with Eurasia. The collision developed immense pressure that caused lower part of Indo-Pakistani crust to thrust under Eurasia and the upper to rise as the Himalayan Ranges. Normally two continental crusts do not descend under one another except in unusual circumstances like that which occurred in the Himalayas. Here Indo-Pakistani continental plate moving north has forced itself under Eurasia and doubled the thickness of the crust (up to 60–70 km) under the Himalayas. The part of crust that rose up to form Himalayan Ranges is mainly comprised of sedimentary rock (limestone) of shallow marine origin that contains microfossil (petrified remains of marine life). Occurrence of these fossils in the high Himalayan rocks suggests that originating on sea floor these rocks have been raised to heights of over 8000 m above the sea level. The buckling of Indo-Pakistani plate under Eurasia and rising up of crust to form Himalayas has caused significant north-south reduction of the crust. Since the full contact of the Indo-Pakistani plate with mainland Eurasia, some 25 to 5 Ma. Ago, about 1000 to 2000 km of the crust south of the Himalayas in India has been shortened. As the under thrusting of the crust and rising of the Himalayas still continue, India is further losing its territory mainly under the Himalayas at the rate of about 4 to 6 cm per year.
 
SHAPING THE EARTH

            Now let us briefly go through the road log of major events that brought the continents and oceans to the present configuration
§         By end of Jurassic, 140 Ma ago, new ocean floor separated Antarctica-Australia from Africa-South America and South Atlantic was created. North Atlantic and Indian oceans were enlarged but the Terhys continued to close. Indo-Pak subcontinent was well underway on its northerly voyage.
§         By end of Cretaceous, 65 Ma ago, the south Atlantic had widened, Madagascar had split away from Africa and the Tethys had closed to from an inland sea — the Mediterranean.
§         About 65 Ma ago, Indo-Pak subcontinent collided with Eurasia ending its trip across the ocean, although it is still pushing northwards.
§         Indo-Pak subcontinent came in full contact with Eurasia, 25 to 5 Ma ago and indentation of the Indo-Pak subcontinent into Eurasia began
§         Australia separated from Antarctica.
               
THE WORLD TODAY
            Present configuration of continents and oceans world over started taking shape at the close of Cretaceous (~65 Ma ago), some 135 million year after drifting of Indo-Pak subcontinent began. End result, following some of the major drift-related events, are summarized as:
§         Himalayas were raised as a result of collision of Indo-Pak subcontinent with Eurasia.
§         Northerly push of the subcontinent that raised the Himalayas continues even today and is making the mountains rise yet higher.
§         Considerable part of Indian crust has been lost due to under thrusting and doubling of the continental crust under the Himalayas. Some portion of crust was also used in elevating the Himaliyas to over 8000 m.
§         The ancient continent Pangaea existed in ancestral Panthalassa, which is now represented by the Pacific Ocean.
§         Tethys Sea shrank into present day Mediterranean.
§         Madagascar (Malagasy) split away from Africa.
§         Antarctica, Australia, Africa and South America, which after breaking of Gondwanaland, were close to each other, separated considerably. As South Atlantic widened South America drifted farthest to get attached with the North America.
 
REFERENCES
Chernicoff, S., Geology (2nded 1999): Houghton Mifflin Company, Boston
Powell, C. McA, 1979: A Speculative Tectonic History of Pakistan and Surroundings: Some Constraints from the Indian Ocean in Geodyanmics of Pakistan: Fahrah and DeJong (eds), Geological Survey of Pakistan, Quetta Pakistan.
Press, F. and Siever, R., 2002: Understanding Earth (3rd ed) W. H. Freeman  and Company, New York. U.S.A.Inc. New York. U. S. A.
            New York. U.S.A
 
Glossary
1. ocean floor spreading: the mechanism by new oceanic crust is created, by magma issuing from mid-oceanic ridges, as adjacent plates move apart. By this process ocean floor spreads a few centimetres per year.
2. Theory of Plate Tectonic: a concept according to which tectonic plates are believed to move on molten upper mantle.
3. lithospheric plates (tectonic plates): One of the dozen plates, composed of crust and upper mantle, that form the outer most rigid layer of earth.
4. subduction: the  process in which one tectonic plate descends below an other.
5. fault: a crack in Earth’s crust along which motion has occurred
 
Curtsy to Monthly Sangat Quetta.