kiel tramped across the glens as the snows melted and retreated , and when the warm season approached , he made his way to the north , where the stony brooks ran down from the mountains , tumbling in waterfalls down steep , rocky banks , where the wind swept up the wild sherin flowers on their branches , and lilac petals wafted and swirled in the air , cascading like snow upon the land , and where the ceiras birds sang mournfully over the bright , sandy shores of lake firien .