Skandapurana 16.335

Īśvara said: / Then one should go to the west, on the auspicious bank of the Nyaṅkumatī, / where, situated toward the southern quarter, lies a sacred ford of great splendour,

renowned as Śaṅkhāvarta, where there is a rock marked with variegated signs, / self-manifest, O great goddess, containing red [veins] within, and exceedingly beautiful.

Even today, when it is cut, bright red is seen right there. / For that is declared to be a Viṣṇu-kṣetra, where Śaṅkha was slain of old,

who had stolen the Vedas, O ruler of the gods, by the all-powerful Viṣṇu. / The sacred ford Śaṅkhodaka was made [there], and it appears in the shape of a conch shell.

By bathing there, O goddess, a man is freed from the murder of a brahmin. / Even for a śūdra, the status of a brahmin is produced for seven births.

Having gone there first, one should then proceed to Rudragayā. / A gift of a cow must be given there by those who desire the full fruit of the pilgrimage.

Thus ends the three hundred and thirty-fifth chapter, entitled “Description of the Māhātmya of Śaṅkhāvartatīrtha,” in the first [sub-section], Prabhāsakṣetramāhātmya, of the seventh section, Prabhāsakhaṇḍa, in the glorious Skanda Mahāpurāṇa, a compendium of eighty-one thousand [verses].