thither , as was earlier told , ungoliant had fled from the whips of the balrogs , and there she dwelt a while , filling the ravines with her deadly gloom , and there still , when she had passed away , her foul offspring lurked and wove their evil nets ; and the thin waters that spilled from ered gorgoroth were defiled , and perilous to drink , for the hearts of those that tasted them were filled with shadows of madness and despair .