IN MAPS of North-west India, the River Ghaggar appears as a small drainage system, flanked by the giant Sutlej to the north and the Yamuna to the south-east. The rivers and its tributaries originate in the Siwalik Hills, meander through the plains of Haryana and Rajasthan where it is called the Hakra and disappears in the sands of western Haryana-Rajasthan near Sirsa. There are claims though made by various Hindu groups such as the Sarasvati Nadi Shodh Sansthan and the Bharatiya Itihasa Sankalan Samiti that this rather unremarkable river has had a much more impressive past. These and other groups claim that the Ghaggar is in fact the Vedic Sarasvati. The Rig Veda describes the Sarasvati as an important river along with the Indus, Sutlej, Ganga and Yamuna.
For many years supporters of this view were using a combination of the Rig Veda and archaeology as evidence that the Ghaggar is the Vedic Sarasvati. Lately though a different kind of evidence has been brought to bear on this problem—the geological history of the Ghaggar. If geological evidence shows that the Ghaggar was in the past a mighty river and one that had a glacial source, it would fit descriptions in the Rig Veda of a large Sarasvati flowing from the mountains to the sea. More importantly it would allow Hindu religious groups to claim that the Vedic people were present in Northwest India much before the Ghaggar dried up about 1800 BC. That would strengthen their claim that the Harappan civilisation represents the beginning of Vedic civilisation in India. To that end a lot of effort has been undertaken to generate and collect geological data that supports this view. This data comes in three flavours: geomorphologic, petrologic and geochemical. Supporters claim that taken together these three types of data show beyond doubt that the Ghaggar is the Vedic Sarasvati. A more critical viewing of the data does not inspire such confidence.
During their lifetime, rivers meander and cut new channels. The older abandoned channels can be seen in satellite images as dark curvilinear features. This technique of using images to delineate channels has spurred a lively industry of Sarasvati mappers to trace a maze of paleo-channels surrounding the Ghaggar and extending into the Thar Desert. These traced maps are then used to claim that in the past the Ghaggar had a lot more water in it and that some of these channels represent the Sutlej River which according to them used to flow into the Ghaggar but has changed course and joined the Indus only in recent times. A common element of all these claims is to emphasise that these paleo-channels are as wide as 8-10 km, an indication of a very large river.
There is some real data buried amongst these exaggerations but it does not support the main claim which is that the Sutlej was a tributary of the Ghaggar. No such large channel has been convincingly demonstrated as the Sutlej. And the figures of 8-10 km wide channels are misleading. What has been mapped are the flood plains and channel system. Flood plains of rivers are very wide and appear dark in images because they contain sediment with higher amounts of moisture. This does not mean that the active river channel at any one point in time was very wide. So the evidence from ancient drainage patterns show that the Ghaggar changed course several times in the past and contained more water than it does today. It doesn’t show that the Sutlej or for that matter the Yamuna were tributaries of the Ghaggar.
The second type of evidence for the Vedic Sarasvati is based on the sediment composition found in the Markanda and Somb, tributaries of the Ghaggar originating in the Siwaliks. A few years ago V V Puri, a glaciologist who had been working on the Markanda river sediments announced that he had found pebbles composed of high grade metamorphic rocks in some of the river terraces that were around 5,500 years old. He argued that since the Markanda river today flows only through the sedimentary rocks of the Siwaliks, the presence of metamorphic pebbles means that in the past the Markanda river was receiving sediments from streams draining a metamorphic terrain and that source was cut off sometime later. He identified this source metamorphic terrain as the Jutogh formation of the high crystalline glacial Himalayas. This, he said is irrefutable evidence that the Ghaggar had a glacial source in the past, fitting the description of the Vedic Sarasvati.
This analysis, however, ignores the complex sediment distribution patterns which are in play in Himalayan style collisional basins. The Siwaliks may be sedimentary but they are often composed of pebbles and boulders of metamorphic rocks. When sediments which would in the future become rocks of the Siwaliks hills were being deposited, streams eroding the metamorphic Jutogh formation transported and deposited metamorphic pebbles and boulders in layers known as conglomerates. Later as the Siwalik sediments were consolidated and uplifted as the Siwalik hills a new drainage developed. This drainage represented by the Markanda River started eroding the Siwalik conglomerates and received from them metamorphic pebbles and boulders. This way streams can contain metamorphic pebbles without actually draining a metamorphic source rock. The pebbles have been recycled into the recent streams via an intermediate Siwalik sedimentary source. The presence of metamorphic pebbles is not irrefutable evidence of a glacial source for the Ghaggar. Yet Dr Puri and other Sarasvati supporters continue to present this data as a game clincher.
The third type of evidence is based on the oxygen isotope composition of ancient water in Ghaggar paleo-channels and the strontium andneodymium isotope composition of Ghaggar sediment. During precipitation, the lighter isotope of oxygen will become preferentially enriched in the vapour phase. As clouds lose moisture and rise from the foothills to high elevations they become progressively enriched in the lighter isotope. Glacial derived water therefore will be isotopically lighter than water from Himalayan foothills. The Bhabha Atomic Research Centre has analysed groundwater trapped in paleo-channels in Rajasthan identified as belonging to the Ghaggar-Hakra system. The analysis shows that the water is ancient and is isotopically heavier than water from known glacial sources. This indicates that the Ghaggar was never fed by glaciers.
A similar conclusion has been drawn by a separate study using strontium and neodymium isotopes of Ghaggar sediment. Rocks from the high crystalline Himalayas have a typical signature that Ghaggar sediments lack. Again, this points to the ancient Ghaggar being a Siwalik fed river. Sarasvati supporters ignore these findings or more bizarrely claim the opposite. They also point out that these aquifers contain fresh water indicating a subterranean Sarasvati still connected to the Himalayas. This is debatable and does not answer the question whether the ancient Ghaggar was sourced from the Siwaliks or from glaciers.
Just how and when did the Ghaggar dry up? Here too a belief that the Sarasvati arose in the glacial Himalayas has led to a preference for the tectonic theory of river desiccation over the better supported climate change theory. The tectonic theory says that the Sutlej and Yamuna—both glacially sourced—flowed into the Ghaggar and tectonic events diverted these channels away drying up the Ghaggar/Sarasvati. To date there has been no serious study that has identified a specific location where this deformation took place and no work that has timed any deformation event to show that it was recent enough to have affected Harappan civilisation.
On the other hand climate data collected from dried up lake sediments in the Thar, the deep sea Indus fan and pollen from Himalayan peat all point to an early Holocene wet phase ending around 3500 BC. North-west India began to dry up although eastwards in the Siwaliks the monsoons were still strong. The Ghaggar would have had enough water to support human habitation due to a wetter source area. By 1800 BC the Thar had totally dried up, rainfall in the source region also decreased and the Ghaggar became too dry to support human activity. Drying progressed from west to east, a trend tracked by shifting human settlements. Younger Harappan and Painted Grey Ware sites (1800–400 BC) occur in eastern Thar and the Ganga Yamuna plains. These patterns cannot be explained by a tectonic theory of river desiccation.
Attempts by Sarasvati revivalist groups to use geological data to equate the Ghaggar with the Vedic Sarasvati have been compromised by the application of poor science and sins of exaggeration and omission. The propaganda however continues. A false geological narrative is being constructed and disseminated. Whether the Vedic people were present on the plains of Haryana and Punjab before the Ghaggar dried up and whether they are the same people who built the Harappan civilisation is not a question that geology can answer. That battle is for archaeologists and linguists. One hopes it is settled by good science and not dogma.