From Atlas and Cyclopedia of Ireland (1900)
NAME.—The county was named from the town of Sligo, which itself took its name from the river Sligeach, river of sligs or shells—shelly river. This river is now called the Garrogue.
SIZE AND POPULATION.—Length from the river Moy to the Arigna River, 40 ¾ miles; breadth from the Lough Gara to Donegal Bay, 38 ½ miles; area, 721 ½ square miles; population, 111,578.
SURFACE.—The eastern part of the barony of Carbury, and the southern shores of Lough Gill, are mountainous. A line of highlands runs from Ballysadare Bay southwest toward Foxford in Mayo, having two moderately level districts on both sides. The rest of the country is level, interspersed with hilly land.
MOUNTAINS AND HILLS.—The Ox Mountains begin immediately southwest of Ballysadare, and run west-southwest to the boundary of Mayo, where they are continued to the southwest by the Slieve Gamph range, which runs first on the boundary of the two counties, and then into Mayo. The Ox Mountains have several summits from 1,200 to 1,800 feet high; and Slieve Gamph attains an elevation of 1,363 feet.
The eastern part of the barony of Carbury, in the north of the county, is a mass of mountains. The highest is Truskmore (2,113) near the boundary, whose summit is in Sligo, but a part of the eastern slope is in Leitrim. Far more striking and remarkable, however, through not so elevated, is Benbulbin (1,722), in the middle of the barony, presenting a scarped precipitious face to Sligo Bay; and a mile and a half south of it is Kings Mountain (1,527). Four miles west of Sligo town is the remarkable isolated flat-topped hill of Knocknarea (1,078), rising with a scarped rocky face over the beautiful plain that lies between its base and the sea. Rising directly over the south shore of Lough Gill are the two hills, Slish (967), and Slievedaeane (900).
In the east of the barony of Tirerrill, near the boundary, is a range called Bralieve, running from northwest to southeast, and rising to 1,498 feet at its highest point. In the southeast, near Ballinafad, the Curlieu Hills run on the boundary with Roscommon. In this southeast part of the county the most remarkable hill is Keishcorran (1,183), which has on its western face a precipitous escarpment pierced with some interesting caves. Near this on the east is Carrowkee (1,062) over the western shore of Lough Arrow.
COAST LINE.—The coast is an alternation of low sharp rocks and flat sandy beaches, relieved by a few bold headlands, and in one place by the grand cliff of Knocknarea.
HEADLANDS.—Lenadoon Point marks the eastern entrance to Killala Bay; Aughirs Point projects north into Sligo Bay; Killaspug Point is the extremity of the peninsula northeast of Ballysadare Bay; Roskeeragh Point stands forth at the extremity of the peninsula that separates Donegal Bay from Sligo Bay; and at the north extremity of the county is another Roskeeragh Point, near which is the rocky projection of Mullaghmore.
ISLANDS.—Maguire's Island lies beside Killaspug Point; Coney Island, about a mile in length, is at the entrance to Cummeen Strand; and at the north side of the same strand is Oyster Island, with a lighthouse. Just outside Coney Island is Black Rock, with a lighthouse; and near Roskeeragh Point is a rocky cluster, one of which is called Seal Rocks. Northeast of this, beside the coast at Cliffony, are Conor's Island and Dernish Island. But the most remarkable island belonging to Sligo is Inishmurray, in Donegal Bay, a mile in length; containing the ruins of the ancient monastery of St. Laserian or Molaise (pron. Molasha); the few inhabitants are very primitive, and have many curious customs.
BAYS AND HARBORS.—Killala Bay separates Sligo from Mayo. Sligo Bay opens eastward, and branches into three inlets: Ballysadare Bay; a middle branch which runs up to the town of Sligo; and Drumcliff Bay, all very sandy.
RIVERS.—The Moy rises at a high elevation among the Ox Mountains, about 2 miles east of Lough Easky; flows first southeast, then southwest, till it enters Mayo; turning northward, it touches Sligo at a point 2 ½ miles above Ballina, from which point to its mouth it forms the boundary between Sligo and Mayo. Its chief Sligo tributaries are: the Mad River and the Owenaher from the Ox Mountains; the Lough Talt River issuing from Lough Talt in Slieve Gamph; and on the south bank, the Owengarve and the Mullaghanoe. The Leaffony River flows into Killala Bay. The Easky River is a mountain torrent rising in Lough Easky high up among the Ox Mountains, and falling into the sea near the village of Easky.
The Ballysadare River falls into the head of Ballysadare Bay at Ballysadare; immediately below the village it tumbles over a series of shelving rocks, forming one of the finest rapids in Ireland. The chief tributaries of the Ballysadare River are: the Owenmore, which rises in the south near Lough Gara; the Owenboy, which rises near the source of the Moy, takes the name of Owenbeg below the village of Collooney, and joins the Owenmore 1 ½ miles above Collooney; and the Unshin River or Arrow River, which issues from Lough Arrow, and flowing northward joins the Owenmore.
In the southeast of the county, the Feorish enters Roscommon. The Bonet River forms the boundary between Sligo and Leitrim for a mile. The Sligo River or the Garrogue, issues from Lough Gill, and after a course of 3 miles falls into Sligo bay at Sligo town. North of Sligo town, the Drumcliff River flows west into Drumcliff Bay. And in the extreme north the Duff forms part of the boundary between Leitrim and Sligo, and falls into Donegal Bay.
LAKES.—Lough Arrow, in the southeast, is 4 miles long, contains 8 square miles, and is studded with a number of beautiful wooded islets; Lough Gara, on the southern border, is 5 miles long, and contains 7 square miles. Lough Gill is 5 ½ miles long and contains 5 ½ square miles; its shores are wooded, and at the south side overhung by mountains; it contains several lovely islands, and altogether it is one of the most beautiful lakes in Ireland—almost rivaling the Lakes of Killarney.
The other lakes on the boundary are, north of Lough Gill, Glencar Lake, chiefly belonging to Leitrim; in the northern extremity, Cloonty Lake near Cliffony; and the southeast, Skean Lake, more than half of which is in Roscommon.
The following lakes are in the interior: Lough Easky at an elevation of 607 feet among the Ox Mountains; it is more than a mile long, and sends forth the river Easky northward; and five miles southwest of it, in Slieve Gamph, Lough Talt, about the same size. Near Ballymote is Templehouse Lake, a mile and a half long; near the south end of which is Cloonacleigha Lake. Two miles south of Collooney is Toberscanavan Lake; and at the same distance northeast of Collooney, is Ballydawley Lake.
TOWNS.—Sligo (10,808), the assize town, on the Sligo or Garrogue River, with good trade and commerce; situated in the midst of a most picturesque country; containing the beautiful ruin of Sligo Abbey, founded in 1252. Ballymote (1,145) in the southeast, with the ruins of a castle and of a friary near it; Tobercurry (1,081), in the southwest. Ardnaree, the Sligo suburb of Ballina, has 1,442 inhabitants.
MINERALS.—The eastern projection of the barony of Tirerrill, approaching Lough Allen, belongs to the Connaught coalfield, and a portion of it is also included in the Arigna iron district. Lead and copper mines were formerly worked in the Ox Mountains; but the works have been long since discontinued.
ANCIENT DIVISIONS AND DESIGNATIONS.—The barony of Tireragh formed a part of the territory of Hy Fiachrach of the Moy (for which see Mayo). The following baronies represent ancient territories: Carbury (there were several other Carburys in Ireland); Leiny, the ancient Luighne; Tirerrill, the ancient Tir-Oililla; Corran, and Coolavin, the principality of Mac Dermott. Immediately east of Lough Arrow, in the parish of Kilmactranny, is the Northern Moytura, or Moytura of the Formorians, where, 27 years after the battle of the Southern Moytura (for which see Mayo), was fought a battle between the Dedannans and the Formorians, in which the Formorians were defeated and slaughtered. Like the Southern Moytura, the plain abounds in sepulchral monuments to this day. At Drumcliff, 4 miles north of Sligo, there was in old times a great religious establishment; and there still remain the ruins of a round tower and some Celtic crosses in a fair state of preservation.