sentences:  The fell's boundaries are clearly defined to the north, west and east by valleys and streams.The western side falls to Borrowdale and the infant River Derwent, the eastern flank descends to the Langstrath valley and its beck while the northern slopes go down to the Stonethwaite valley.To the south, Rosthwaite Fell is linked to the higher and better known fell of Glaramara by a marshy and undulating ridge which goes over several subsidiary tops on the way.