Geltsdale & Glendue Fells

Geltsdale & Glendue Fells is a Site of Special Scientific Interest in the North Pennines, England. The site has an area of 8059 ha, partly in Cumbria and partly in Northumberland.

Etymology
Eilert Ekwall judged that the name Glendue comes from the now dead Cumbric language, comprising the words found in modern Welsh as glyn 'valley' and du 'black', with Victor Watts adding that 'Glendue is one of the narrowest and darkest valleys in S Tyndale'. Although it has been noted that name could come from the equivalent Scottish Gaelic words, scholars view the Cumbric etymology as more likely.

Birdlife
It is noted for its ornithological interest and the greater part of the area is managed as a RSPB reserve for upland birds. It is one of a group of SSSIs underlying the North Pennines Moors Special Protection Area, which was designated in 2001 under the Birds Directive.