From Straupe to Brasla water reservoir its primeval valley reaches a depth of 15 m, while from there on to its mouth with Gauja (less affected section) – up to 30 m deep and 300 m wide „canyon“. The deepest section of the primeval valley was shaped by the melting waters of a glacier 12 000 years ago. This is among the most beautiful river sections in Latvia, where the reddish and yellowish sandstone outcrops from Gauja suite are seen.