Only three rise 150 metres (490 ft) or more above the surrounding terrain: The Cheviot itself, Shillhope Law and Housedon Hill, a small northern outlier (see Marilyn).

These are in turn intruded by a swarm of igneous dykes with a predominantly calc-alkaline chemistry arranged radially around the pluton.

[4] Both the pluton and the volcanic rocks owe their origin to the northward subduction of the oceanic crust attached to the former micro-continent of Avalonia beneath the Laurentian plate in the course of the Caledonian orogeny during the Ordovician and Silurian periods.

[5][6] The surrounding lower ground is formed from Carboniferous Limestone, though much of it is obscured by superficial deposits of Quaternary age.

In addition, a sparse network of public bridleways and footpaths stretches around the area, often providing useful means of access from the lower ground onto the open hills.

[7] Many walking routes have been established, such as: The Otterburn Army Training Estate (ATE) covers about 230 square kilometres (90 sq mi) of the Southern Cheviots, approximately 23% of the Northumberland National Park.

Otterburn is the UK's largest firing range, and is in frequent use — artillery can be clearly heard from Lindisfarne to the north-east and Fontburn Reservoir in the south.

[11][12][13] The peaks marked with a warning sign () lie within the danger area of the ATE Otterburn artillery range.