The south slope rises precipitously from the foothills; the north slope is more gradual, but it is much broken by rugged spurs and deep gorges.
In the north-west it includes spurs of the Taunus.
It has been suggested that these spurs represent the sites of vents or fissures of eruption.
Of the Irun-Bayonne road, along mountain spurs to the Great Rhune, 2800 ft.
Birdwood's force had taken root since April were spurs of a tangled mountain mass known as Sari Bair, from the topmost ridges of which the Straits about the Narrows were partially visible at a distance of 4 or 5 miles.