The further tops of Low How (497 m) and Cockley Moor (455 m) are passed before this branch of the ridge peters out in extensive conifer plantations, and then the ground climbs again to Great Mell Fell. The northern branch of the ridge is edged by Wolf Crags above the Old Coach Road, beyond which a wide grassy moor sweeps north across Sandbeds Moss and Flaska to the A66 road and the dismantled Penrith to Keswick railway. Great Dodd stands on the watershed between the Eden river system to the east and the Derwent river system to the west. Its western slopes used to drain into St John's Beck, a tributary of the River Greta, which in turn joins the River Derwent at Keswick. When Thirlmere Reservoir was constructed in the late 19th century, two of Great Dodd's western streams, Ladknott Gill and Mill Gill, were captured by a water leat and diverted into the new reservoir. The northern slopes of Great Dodd drain either into Mosedale and Mosedale Beck or into Trout Beck. These also flow into the River Greta (via the River Glenderamackin) and then to the Derwent. However, the eastern and southern slopes of Great Dodd drain into Deepdale and Aira Beck, which flows into Ullswater. The lake drains into the River Eamont, which then joins the River Eden near Penrith. The beck in Deepdale undergoes a number of name changes. Beginning as Browndale Beck as it flows through the hanging valley of Deepdale, it becomes Rush Gill as it drops to Dowthwaitehead, and is then called Aira Beck. This is the head stream for the famous waterfall of Aira Force, a popular tourist sight. Similarly, Groove Beck, which rises on Matterdale Common, the north-east ridge of Great Dodd, becomes Thornsgill Beck and then Trout Beck, before joining the River Glenderamackin. There are no tarns on Great Dodd, and very few exposures of rock. Small crags do line the lower western slopes above St John's in the Vale. Lad Knott is the most prominent of these, and the deep ravine of Mill Gill also exposes the rock. On the north-east ridge Randerside, Wolf Crags and Dowthwaite Crag all display the rocks. Routes Nearly all of Great Dodd (above the intake walls in the valleys) is Open Access land. The north-east ridge is part of Matterdale Common, owned by the National Trust. Ascents of Great Dodd can begin