Matsya Purana — Solar–Lunar Motions
परिगच्छति सूर्यो ऽसौ मासं काष्ठामुदग्दिनात् मध्येन पुष्करस्याथ भ्रमते दक्षिणायने //
parigacchati sūryo 'sau māsaṃ kāṣṭhāmudagdināt madhyena puṣkarasyātha bhramate dakṣiṇāyane //
From the eastern direction, that Sun traverses the (directional) quarter for a month; then, passing through the midst of Puṣkara, it turns and continues its circuit during the southern course (Dakṣiṇāyana).
It does not describe Pralaya directly; it maps the Sun’s monthly movement and its turning into Dakṣiṇāyana, part of the Purāṇic framework for cosmic time-order rather than dissolution.
By defining Dakṣiṇāyana and the Sun’s course, it supports dharmic calendrics—choosing proper seasons/months for royal rites, ancestral offerings (pitṛ-karmas), and household saṃskāras aligned with the ayanas.
Ritually, ayana-based timing guides festivals and śrāddha seasons; architecturally, directional awareness (kāṣṭhā) and solar movement inform orientation principles used in Matsya Purana–style Vastu planning (east-facing sanctums and light/solar considerations).