The
North-Western Fells occupy the area between the rivers Derwent and Cocker, a broadly oval swathe of hilly country, elongated on a north–south axis. Two roads cross from east to west, dividing the fells into three convenient groups. The central sector, rising between
Whinlatter Pass and
Newlands Pass, includes Grasmoor. The highest ground in the North-Western Fells is an east–west ridge in this central sector, beginning with Grasmoor above Crummock Water and then gradually descending eastwards over Crag Hill,
Sail,
Scar Crags and
Causey Pike. Grasmoor has the greatest elevation, although Crag Hill stands at the hub of the range. From the valley floor near Little Town at the eastern end, the ridge requires of gradual ascent to attain the summit of Grasmoor. Starting at the shores of Crummock Water in the west, the same is achieved by a single slope of scree in less than a quarter of the distance. Grasmoor is Lakeland's terminal height
par excellence. The summit is at the west end of a broad, gently domed promenade of moss and short grass, with a narrowing in the middle where the deep bowl of Dove Crags bites into the northern face. To the east of this plateau are broad smooth slopes descending to a wide unnamed
col at . This connects onward to Crag Hill. At the western end the summit area narrows, culminating at the subsidiary top of Grasmoor End () which crowns the western face. Great fans of scree descend to the lakeside road below. Grasmoor has one minor ridge which descends south-westward over Lad Hows () before a steeper fall to the valley floor. To the south of Grasmoor is the valley of Rannerdale, which flows to Crummock Water between Lad Hows and the neighbouring
Wandope. This drainage is supplemented by Cinderdale Beck, separating Lad Hows from the main body of the fell. The northern flank of the ridge stands above Liza Beck, in the valley of Gasgale Gill. This stream also makes due west for Crummock Water, but is diverted northward by the low top of Lanthwaite Hill to join the Cocker after its exit from the lake. An area of lowland to the north-west is thus annexed to Grasmoor from the natural territory of
Whiteside. ==Geology==