Donegal tweed manufactured for centuries it took on its modern form in the 1880s, largely due to the pioneering work of English philanthropist Alice Rowland Hart. While the weavers in County Donegal produce a number of different tweed fabrics, including herringbone and check patterns, the area is best known for a plain-weave cloth of differently-coloured warp and weft, with small pieces of yarn in various colours woven in at irregular intervals to produce a heathered effect. Such fabric is often labelled as "donegal" (with a lowercase "d") regardless of its provenance. Along with Harris Tweed manufactured in the Scottish Highlands, Donegal is
Donegal batholith Dalradian and the granodiorite. These early phases were followed by the emplacement of a large volume of porphyritic monzogranites at a time when the granodiorite and tonalite had cooled sufficiently to fracture. This pluton lies at the southwestern end of the Main Donegal granite. Three distinct types of granite are recognised, an outer biotite monzogranite inside which there is a body of biotite-muscovite monzogranite and in the centre is an aplitic biotite-muscovite microgranite. The intrusion is interpreted to have the form of a laccolith. The main part of the pluton shows only weak evidence of deformation. Studies of the anisotropy