Occasionally, the Cheviot Hills, which straddle the border between England and Scotland, are included in more broad definitions of the range. However, they are of mainly [[Igneous rock|igneous]] origin, making them geologically distinct from the largely limestone (sedimentary) rocks of the Pennines. | Occasionally, the Cheviot Hills, which straddle the border between England and Scotland, are included in more broad definitions of the range. However, they are of mainly [[Igneous rock|igneous]] origin, making them geologically distinct from the largely limestone (sedimentary) rocks of the Pennines. |