Matsya Purana — Measures of Time: Caturyuga Computation
पूर्वं कृतयुगं नाम ततस्त्रेताभिधीयते द्वापरं च कलिश्चैव युगानि परिकल्पयेत् //
pūrvaṃ kṛtayugaṃ nāma tatastretābhidhīyate dvāparaṃ ca kaliścaiva yugāni parikalpayet //
First comes the age called Kṛta (Satya); after that it is known as Tretā; then come Dvāpara and Kali—thus one should conceive the yugas as a fourfold cycle.
It does not describe Pralaya directly; it establishes the ordered framework of cosmic time (the four yugas) within which creation, preservation, and dissolution narratives are situated.
By defining the four yugas, it implies that standards of conduct and governance are understood against a changing moral climate; kings and householders are taught to uphold dharma appropriate to the age, especially amid decline toward Kali.
No specific Vāstu or ritual rule is stated; the verse provides the chronological scaffold often used to contextualize when rites, temple traditions, or dharma-standards are said to flourish or diminish across yugas.