Matsya Purana — Cosmography of Śākadvīpa and Successive Dvīpas: Mountains
ततः परं प्रवक्ष्यामि क्रौञ्चद्वीपं यथा तथा कुशद्वीपस्य विस्ताराद् द्विगुणस्तस्य विस्तरः //
tataḥ paraṃ pravakṣyāmi krauñcadvīpaṃ yathā tathā kuśadvīpasya vistārād dviguṇastasya vistaraḥ //
Next, I shall explain Krauñcadvīpa in proper order; its extent is said to be twice the breadth of Kuśadvīpa.
This verse does not describe Pralaya; it belongs to the cosmographic section, giving a proportional measure of Krauñcadvīpa relative to Kuśadvīpa.
Directly, it does not prescribe dharma; indirectly, it supports the Purāṇic ideal that rulers and householders should know sacred geography for pilgrimage, ritual orientation, and worldview (dharma grounded in cosmic order).
No explicit Vāstu or ritual rule is stated; the main technical point is measurement-by-proportion (dviguṇa), a Purāṇic way of structuring cosmic space that also informs how later traditions imagine sacred layouts and directions.