About formation of river ganga

At river Ganges people go for pilgrimage and they wash themselves and clean themselves because they believe that all their sins will been forgiven and that they can go to heaven it's mostly Hindus that believe this. The story behind it is :

The was a man called Kapila and another man called King Sagara and he had six thousand sons and they disturbed Kapila when he was meditating and Kapila opened his eyes and all six thousand sons where burnt into ashes. King Bhagiratha wants to bring back his ancestors which are the sons of King Sagara. So he is granted his wish and Ganga has to fall to earth but all that power would destroy earth. Shiva uses his hair to catch Ganga but she dies and her ashes fall into the river. People go there because the ashes from a goddess that fell from heaven is there.