What stopping a river entails

I magine yourself as a bird soaring high up in the sky. Your bird’s-eye view of the unfolding landscape far below includes a silvery ribbon meandering along mountain slopes. You follow this ribbon as it gets wider and wider and then breaks up into several tributaries before it finally gets swallowed up by the ocean. Yes, this shimmering ribbon is a river. It may have been born from a tiny spring gushing out of the earth or from the melting snows of mountain peaks.