Tirtha Shraddha is the name given to a specific sort of
shraddha (ancestral memorial ceremony) that is done while visiting a pilgrimage
site (tirtha).
A shraddha includes two main features: symbolically feeding
one's ancestor(s) by providing fried grain balls (pindas) and serving actual
food to a group of brahmins who symbolize one's ancestors.
Tirtha shraddhas fall under the category of occasional deeds
(naimittika karma) since they are only required under particular circumstances.
This step would not be necessary under normal circumstances,
but it is required while visiting a pilgrimage site.
Traditional pilgrimage literature, most of it authored by
brahmins who received such meals and other gifts, is adamant that this
commitment should not be overlooked.