Matsya Purana — Solar–Lunar Motions
काष्ठयोरन्तरं ह्येतद् योजनानां प्रकीर्तितम् काष्ठयोर्लेखयोश्चैव अयने दक्षिणोत्तरे //
kāṣṭhayorantaraṃ hyetad yojanānāṃ prakīrtitam kāṣṭhayorlekhayoścaiva ayane dakṣiṇottare //
This is declared to be the interval, measured in yojanas, between the two kāṣṭhās; and likewise the interval between the two lines (lekhā) in the sun’s southern and northern courses, namely dakṣiṇāyana and uttarāyana.
This verse is not about pralaya; it focuses on technical measurement—distances expressed in yojanas—and relates them to the sun’s southern and northern courses (dakṣiṇāyana/uttarāyana).
Indirectly, it supports correct calendrical and spatial reckoning used for governance and household ritual timing—especially determining seasonal halves of the year (ayana) for ceremonies and administrative planning.
By defining intervals and reference-lines/markers (kāṣṭhā, lekhā) tied to the ayanas, it underpins traditional orientation and measurement logic used in Vastu-aligned layouts and in choosing ritually appropriate seasonal timings.