Matsya Purana 248.4

248.4

yacchidramūrdhvamākāśaṃ vivarākṛtitāṃ gatam.
vihitaṃ viśvayogena yadadhastadrasātalam .. 248.4 ..

Again it was divided by Viṣṇu, the Creator and the great Divider, into eight parts The hole in the upper half of it became the sky, and that in the lower half formed the Pâtâla Kâmchanagiri was formed by the water that came out first of the egg created by Viṣṇu for the formation of the Lokas—4-5.