Yesterday we observed the 16th day of periyappa's death. He died on 8th jun, 2009 by a road accident at somanur. Yesterday they went to bhavani-koodudhurai sangamam to do the rituals. We do these rituals to appease the dead persons atma and to get them mukthi or deva loka. On the 16th day of death a persons astral body is dissolved completely and he no longer exists in material/physical shpere.
We know that upon the death of the body the mind cease to exist. (I remember a dialogue from 'The Matrix'-'The body can not exist without mind'). The human beings are composed of five states or bodies namely physical, mental, astral (i forgot others).
The subject is an elaborate one and i will discuss it in a leisurely manner.
The 16th day rituals are done by prokithars in bhavani sangamam. In Gounder (Kongu vellalar) marriage and death rituals and seers are done by vannan (washerman) and navithan (who maintain saloons). The third day would be elaborate one with poojas in cemetry and pongal at well and slokas told by him.
I remember what slokas were told to me for my fathers dead.
'Thahappanar irandhadharkaka tharana varusham, thai masam 13 aam thethi dharma kallai Gangai le vidukirom, Kaveri le vidukirom, kirshna nathi le vidukirom theemai poi, nanmai vandhu sorkanj chera, kailasha morcham undaka.'
It is beleived that dead person has to cross rivers of fire (Agni) in his way to motcha. To help him accomplish we guide him using manthras/slokas. We give him padayal (food and water) for hunger and thirst. The food is taken by kakkai (crows) which will transer it to the dead man.
So many cultures fllows different methods and customs during death ceremonies. It is subject for research scholars for those studying socialogy/humanity.