Mother Ganges replied: When I fall from the sky to the surface of the planet earth, the water will certainly be very forceful. Who will sustain that force? If I am not sustained, I shall pierce the surface of the earth and go down to Rasātala, the Pātāla area of the universe.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
कोऽपि धारयिता वेगं पतन्त्या मे महीतले । अन्यथा भूतलं भित्त्वा नृप यास्ये रसातलम्
ko'pi dhārayitā vegaṃ patantyā me mahītale | anyathā bhūtalaṃ bhittvā nṛpa yāsye rasātalam
SB 9.9.4