From Atlas and Cyclopedia of Ireland (1900)
NAME.—The town of Donegal was so called from an old dun or fortress, which got the name of Dun-nan-Gall, the fortress of the Galls or foreigners—these foreigners being Danes, who settled there at an early period. County named from the town.
SIZE AND POPULATION.—Length from Inishowen Head to Malinmore Head, 84 miles; breadth from Bloody Foreland to the boundary, a little south of Castelfinn, 41 miles; area, 1,870 ½ square miles; population, 206,035.
SURFACE.—Donegal is a region of mountains and long valleys, and there is a large extent of bog and waste. The only moderately level land lies in the east half of the barony of Raphoe, and in the south half of the barony of Tirhugh.
MOUNTAINS AND HILLS.—In the northwest of the county the two ranges of the Derryveagh Mountains and the Glendowan Mountains run parallel, from northeast to southwest, inclosing the splendid valley of Glen Beagh. The highest summit is Dooish (2,147), in the middle of the Derryveagh range, over Lough Beagh. To the west again of the Derryveagh range is a third irregular range, running in the same direction; containing Errigal (2,466), the highest mountain in Donegal, rising over Dunlewy Lake; and northeast of this, Mukish (2,107), a great flat-topped mountain.
Southeast of Gweebarra Bay, and northeast of Glenties, is a fine mountain group, of which Aghla (1,961) forms the center.
The barony of Banagh is traversed from end to end by a range which may be said to cover the whole peninsula. In the east end is the short independent range of Croaghgorm or Bluestack (2,219); and in the west are Slieve League (1,972) rising sheer from the sea on the south coast, and Slieveatooey (1,515) over the sea in like manner on the north coast. This range continues to the northeast through the barony of Raphoe toward Letterkenny, and contains Gaugin (1,865), Boultypatrick (1,415), and Cark (1,205).
The peninsula of Inishowen is in great part mountainous, the culminating summit being Slieve Snaght (2,019) in the center. In the peninsula of Fanad, west of Lough Swilly, is the small but remarkable range of Knockalla (1,203); and Lough Salt Mountain (1,546) rises conspicuously, west of the head of Mulroy Lough.
COASTLINE.—The coast is broken the whole way round, presenting a grand succession of bays, promontories, cliffs, and islands.
HEADLANDS.—Beginning at the northeast: Inishowen Head, the northeast extremity of Inishowen, and Malin Head, its northwest extremity; Dunaff Head and Fanad Head, at both sides of the mouth of Lough Swilly; Horn Head, a lofty rock rising precipitously over the sea at the west side of Sheep Haven; Bloody Foreland; Dawros Head, which is the end of the peninsula of Dawros, between the bays of Gweebarra and Loughros More; Malinmore Head, the most westerly point of Donegal. Carrigan Head, Muckros Head, St. John's Point, and Doorin Point all project south into Donegal Bay. Immediately west of Carrigan Head, Slieve League rises 1,972 feet steep from the sea; and the coast from Carrigan Head round by Glencolumkille to Loughros Bay exhibits the grandest combinations of cliff scenery in Ireland.
ISLANDS.—Tory Island lies 8 miles from the mainland; it is about 2 ½ miles long, and stands out of the sea so as to appear like a great collection of towers and pinnacles; it contains the ruins of an ancient ecclesiastical establishment (including a round tower) founded in the 7th century by St. Columba. Aran Island contains nearly 7 square miles, and rises 750 feet over the sea. North and south of Aran are numerous small islands, the chief of which are Inishsirrer, Gola, Owey, Cruit, Rutland, Inishfree, and Roaninish. The island of Inch in Lough Swilly contains nearly 5 square miles, and has a summit (Inch Top) 732 feet high. The little island of Rathlin O'Byrne is near Malinmore Head. Between Ballyness Bay and Tory are the three small islands, Inishbofin, Inishdooey, and Inishbeg. Northeast of Malin Head is the small rocky island of Inishtrahull, the most northerly land belonging to Ireland.
BAYS AND HARBORS.— The two deep bays, Lough Foyle and Lough Swilly, nearly insulate the barony of Inishowen; Trawbreaga Bay pierces far into Inishowen, south of Malin Head; Mulroy Bay is separated from Lough Swilly by the peninsula of Fanad; Sheep Haven is separated from Mulroy Bay by the peninsula of Rosguill. Ballyness Bay is the usual embarking place for Tory Island. South of Bloody Foreland are the bays of Gweedore and Inishfree; and south of Aran Island are those of Trawenagh and Gweebarra. Separated from Gweebarra Bay by the peninsula of Dawros, are the two bays of Loughrosmore and Loughrosbeg. Glen Bay, overtopped by lofty precipices, opens out from the solitary Glencolumkille; and at the other side of Malinmore Head is Malin Bay, Fintragh Bay, Mac Swyne's Bay, and Inver Bay, which are branches of Donegal Bay.
RIVERS.—The Foyle separates Donegal from Londonderry. The Foyle is formed by two main streams, the Finn and the Mourne, which join at Lifford. The Finn, rising in Lough Finn, and flowing east, belongs wholly to Donegal. The Deele joins the Foyle a mile north of Lifford.
The Eask flows from Lough Eask by Donegal town into Donegal Bay; and of the several small feeders that run into Lough Eask, one, the Lowerymore, is remarkable as traversing the magnificent Gap of Barnesmore. Beside the Eask, Donegal Bay receives from the north the Eany Water at Inver Bay, the Bunlackey near Dunkineely, and the Glen River into Teelin Bay.
In the west of the county, the Owenea and the Owentocker flow into Loughrosmore Bay at Ardara; the Gweebarra into Gweebarra Bay, and the Gweedore into Gweedore Bay. Through Glenbeagh a stream flows northeast, which takes successively the names Owenbeagh, Owenarrow, and Lackagh, falling at last into Sheep Haven. The river Swilly, flows east by Letterkenney into the head of Lough Swilly; and into the same bay flows the Leannan.
Into Donegal Bay, in the extreme south, flow the Erne, having a fine fall at Ballyshannon; and the Bradoge at Bundoran. The little river Termon enters the north end of Lough Erne.
LAKES.—Donegal is noted for its fine mountain lakes with splendid scenery. Lough Erne lies on the south boundary. Eight miles east of Donegal town, and 4 miles north of Pettigo, is Lough Derg, over 3 square miles in extent, and containing St. Patrick's Purgatory, which has been for many ages a celebrated place of pilgrimage. Lough Eask lies 3 miles northeast of Donegal. In the north, Lough Beagh, one of the finest mountain lakes in Ireland, occupies the bottom of Glen Beagh; and lower down, at the mouth of the valley, near the head of Sheep Haven, is Glenlough. Dunlewy Lake and Lough Nacung lie at the very base of Errigal Mountain; and under the opposite base is Lough Altan. East from Gweebarra Bay in the beautiful Lough Finn at the base of Aghla; and near it are the small Lough Muck and Lough Barra.
TOWNS.—Beginning in the southwest and going round the margin: Ballyshannon (2,840) stands at the mouth of the river Erne, near where it forms a fine cascade over a ledge of rocks, the old cataract of Assaroe: there is a salmon fishery; and the town is celebrated in legend and romance. Four miles southwest of Ballyshannon, on the shore of Donegal Bay, is Bundoran (703), a favorite watering place. Donegal (1,416) is in a beautiful situation at the mouth of the river Eask, at the head of an inlet from Donegal Bay, surrounded by hills; just beside it stands the fine old ruins of Donegal Castle, and also the ruins of a monastery. Westward from this is Killybegs (7.64), on the north shore of Donegal Bay—the capital of the peninsula—where a good deal of fishing is carried on. On the north side of the peninsula is Ardara (552); six miles northeast of this is Glenties (487). Passing Dunglow (468) we come to Dunfanaghy (598), near Horn Head, the chief town of all this remote district. Rathmelton (1,406) stands just where the river Leannan falls into Lough Swilly. Letterkenny (2,188) is on the river Swilly, near its mouth; and on the east shore of Lough Swilly is Buncrana (764), a watering place. Moville (1,129) stands on the east shore of Inishowen; and in the interior is Carndonagh (726), the capital of the peninsula. Lifford 511, the assize town, on the Foyle, may be regarded as a part of Strabane, on the Derry side of the River; and the circuit ends at the pretty village of Pettigo (468), near Lough Erne.
The towns in the interior are Raphoe (986), west of Lifford, an ancient episcopal see; and Ballybofey (1,009) and Stranorlar (420), near each other on the river Finn.
MINERALS.—Very fine white marble is found at Dunlewy, at the base of Errigal Mountain. Near Raphoe there is a formation of steatite, a soft kind of stone, easily carved and very durable.
ANCIENT DIVISIONS AND DESIGNATIONS.—Donegal was the ancient Tirconnell, inhabited by the Kinel Connell, who were descended from Conall, son of the great king Niall of the Nine Hostages (A.D. 378-405), and who possessed nearly the whole of Donegal: their inauguration place was the Rock of Doon, near Kilmacrenan.
Four miles northwest of Derry, on a hill, is Greenan-Ely, the ruins of Aileach, the ancient palace of the O'Neills, the kings of Ulster, who were also for many ages the kings of Ireland.