Upper Teesdale is a Site of Special Scientific Interest (SSSI) in the Teesdale district of County Durham, England. It encompasses an extensive upland area that includes the headwaters of the River Tees. The SSSI is one of the most important botanical sites in Britain; the flora is exceptionally rich in species that are nationally rare, including some that are relicts of the arctic-alpine environment of the last glacial period. The area supports internationally important populations of some wading birds and is home to several rare invertebrates. Within the SSSI are several locations that are of national importance geologically, including one of only two known outcrops of 'sugar' limestone in Britain The southern part of the SSSI largely coincides with the eastern portion of the Moor House-Upper Teesdale National Nature Reserve, which has been designated a 'Biosphere Reserve' by UNESCO.The entire area falls within the North Pennines Area of Outstanding Natural Beauty. If you would like to purchase any of the images in this gallery as either a digital download or print please go to my online store by clicking here