In the 1960s, hydrologist Robert Raikes and archaeologist George Dales independently, then together, advanced theories on seasonal flooding, or more precisely the seasonal "pond" of Mohenjo Daro and some smaller sites in the vicinity of Sind. Each scholar felt able to hypothesize, from the perspective of their own separate studies, that a swelling of the land during the Harappan period had produced some sort of natural barrier across the Indus River, perhaps about 10 km wide and up to 45 meters high. . The result of such a phenomenon during the Harappan period would have been an annual inundation of sites as the natural basin engulfing them grew with runoff from the Himalayas. As the warm season approached, the basin would dry up or at least shrink considerably. Associated with such a calamity would have been problems posed by waterborne diseases and waste disposal. Naturally, problems related to food supply and trade would have been exacerbated. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay Archaeological evidence for such an anomaly includes the existence of five or more layers of silt found between the levels of the mature Harappan habitation at Mohenjo Daro. It should be emphasized that this archaeologically attested silt is a type of silt deposited under still water conditions, not under flood water conditions. One can easily imagine that such a situation would have given rise to the use of massive mud brick platforms as the basis for home construction. activities and construction in an attempt to stay high and dry above the flooded lake. So Wheeler was right in defining the massive constructions as defensive constructions; however, they were defended against the intrusion of water, not people. It is also equally reasonable to suggest that the Harappan fixation with the control of water was somehow connected to this phenomenon. Tectonic uplift of the coastline Another natural and uncontrollable factor in the disappearance of at least some of the Indus cities was large-scale tectonic uplift. . The evidence for this is simple and indisputable: Harappan seaports along the Makran coast, such as Sutkagendor, Sotka Koh and Bala Kot, are now located up to 50 km inland. “These displaced ports made it evident that the coast of Pakistan had risen considerably over the last 4,000 years, with the initial rise apparently occurring during the Harappan period” (Dales 1966: 95). The earthquakes associated with such an uplift would have been tremendous, and the disruption of sea and land trade networks would have been devastating. After all, proximity to the Arabian Sea trade routes was the raison d'être of sites like Sutkagen Dor and Sutkha Koh. This tectonic uplift, therefore, would explain the disappearance of numerous Harappan coastal sites, as well as implying difficulties for many other Harappan sites that depended on these coastal sites for trade and/or marine resources. The fall of the Harappan culture Without a doubt, these cities were engineering masterpieces of their time. The remains of their walls provide clues to the culture that thrived in the Indus Valley. Clay deity figurines, for example, are evidence of the importance of religion. Toys and games show that even in 3000 BC children – and perhaps even adults – loved to play. Pottery, textiles and beads are evidence of expert craftsmanship and thriving trade. It was this intense devotion to craftsmanship and trade that allowed the Harappan culture to spread widely and.