New Defender's Study Bible Notes
74:15 cleave the fountain. This must refer to the breaking open of all “the fountains of the great deep” (Genesis 7:11) at the beginning of the Food.
74:15 mighty rivers. The great flood-rivers, which drained the waters off the rising lands after the Flood, were gradually dried up, leaving their evidences in the great valleys and alluvia of all the earth’s rivers. Almost all present-day rivers give evidence of much greater depths and flows in the past.