Sentence:  Carrying light packs they left camp at daylight the next morning. Trails there were none; but they followed the general course of a small creek, crossed a <WSD>divide</WSD>, and dipped down into a beautifully timbered valley watered by a swift, large creek of almost riverlike dimensions. 
Meaning of the word marked with <WSD> tags:  A large chasm, gorge, or ravine between two areas of land.