Impurity of a Field in which a Grave was Lost
Please note that, for the purpose of this document, a "Beit haPeras" is a field in which a grave is known to have existed, and which was plowed over such that the grave cannot be identified.
How much of a field becomes a Beit haPeras if a grave is plowed into it: Temurah 13aThe FieldProcess of Purifying the Field in which a Grave was Lost
Impurity of a Field in which a Grave was Lost is Rabbinic: Berachot 19b; Ketuvot 28b
Allowing a Kohen to acquire this impurity in leaving Israel for a property claim against a Gentile, or to study Torah, or to marry: Eruvin 47a-b
For an Entrant to Blow the dirt away in front of himself as he walks: Berachot 19b; Eruvin 30b; Pesachim 92b, Ketuvot 28bOther laws
Plowing it over: Berachot 19b; Pesachim 92b; Ketuvot 28b
Plowing it over with one's feet, in walking: Eruvin 30b