Matsya Purana — Description of Gomedaka and Puṣkara Dvīpas; the Lokāloka Boundary; Ocean Tide...
आवृत्य तिष्ठति द्वीपः पुष्करः पुष्करैर्वृतः पुष्करेण वृतः श्रीमांश् चित्रसानुमहागिरिः //
āvṛtya tiṣṭhati dvīpaḥ puṣkaraḥ puṣkarairvṛtaḥ puṣkareṇa vṛtaḥ śrīmāṃś citrasānumahāgiriḥ //
Encircling the central region, the island-continent named Puṣkara stands, surrounded by lotus-like expanses; and within Puṣkara, the splendid great mountain called Citrasānu is likewise enclosed.
This verse is cosmographic rather than pralaya-focused; it maps the stable arrangement of Puṣkara-dvīpa and a major mountain within it, reflecting the Purana’s ordered world-structure.
Indirectly, such geography supports dharma by defining sacred space and the broader cosmic order (loka-vyavasthā) that kings protect and householders honor through pilgrimage, ritual orientation, and respect for sacred landscapes.
No explicit Vāstu rule appears, but the emphasis on enclosure/encirclement and central features echoes Purāṇic spatial thinking used in temple-site symbolism—centers (mountain/axis) bounded by concentric zones.