Islands of the Forth
Group of small islands in the Firth of Forth, Scotland.
The Islands of the Forth are a cluster of small islands in the Firth of Forth and the River Forth estuary on Scotland’s east coast. Most sit in the open firth between the Lothians and Fife, mainly east of Edinburgh, with two further west in the estuary. Their geology and history vary widely; over time, several have been linked to both religious sites and military use. Lighthouses and navigation aids have been built on the islands and skerries—one dates back to the 1600s. Only one island now has people living there all year. The area is rich in bird and marine life. The northern gannet’s scientific name comes from its connection to the Bass Rock. Few islands lie off eastern Scotland, and most of any real size are part of this group.
The Isle of May is farthest east, off Fife’s coast south of Crail. South in the outer firth, a group sits off East Lothian near North Berwick and Gullane: from east to west, the Bass Rock (often just “The Bass”), Craigleith, Lamb, Fidra, and Eyebroughy. A second group lies in the inner firth: Inchkeith and Inchcolm off Kinghorn and Aberdour on the north shore, Inchgarvie midway between North and South Queensferry, and Inchmickery and Cramond Island nearer Edinburgh on the south shore. Alloa Inch and Tullibody Inch are farthest west in the river estuary. Only Inchcolm has had recent year-round residents, though monasteries, hermitages, lighthouses, and fortifications once stood on most. In the late 1800s, the Isle of May had over 20 people. Many island names start with “Inch-” (from the Gaelic for “island”).
Geologically, most islands are remnants of igneous intrusions. The Isle of May’s rock is fine-grained, dark-grey basalt with greenish tints and greenstone. Fidra is mostly basalt, and the Bass is a phonolite volcanic plug. Craigleith is a laccolith of essexite, popular for curling stones; Cramond Island is dolerite. Inchmickery and Inchgarvie are igneous, with Inchgarvie partly picrite. Studies of the firth’s underwater landscape show Inchgarvie’s visible surface is just the top of a larger crag-and-tail structure, like Edinburgh Castle and the Royal Mile, shaped by glaciers. The tidal islet Eyebroughy, about 1.5 km west of Fidra, is made of trachyte from the Lower Carboniferous. Most of Inchkeith is volcanic, but it also has sandstone, coal, limestone, and shale—the last rich in fossils—plus several springs. Inchcolm is simi
- location
- Firth of Forth, east coast of Scotland
- number_of_islands
- several, including Isle of May, Bass Rock, Craigleith, Lamb, Fidra, Eyebroughy, Inchkeith, Inchcolm, Inchgarvie, Inchmickery, Cramond Island, Alloa Inch, Tullibody Inch
- geology
- mostly remnants of igneous intrusions (basalt, phonolite, essexite, dolerite, picrite, trachyte)
- notable_feature
- Bass Rock has more than 150,000 nesting northern gannets, the largest single rock gannetry in the world
- human_inhabitants
- only Inchcolm has had a resident population in recent years
- historical_experiment
- In 1493, King James IV directed a dumb woman and two infants be transported to Inchkeith to see what language they would speak
Lore & Background
The Islands of the Forth have a long history of human activity. In the 15th century, during the reign of King James IV, Inchkeith was the site of an extraordinary experiment: a dumb woman and two infants were transported to the island to ascertain which language the infants would grow up to speak when isolated from the rest of the world. According to the historian Robert Lyndsay of Pitscottie, some said they spoke good Hebrew. In 1497, Inchkeith and Inchgarvie were used as an isolated refuge for victims of syphilis, and in 1589, Inchkeith was used to quarantine passengers of a plague-ridden ship. More plague sufferers came from the mainland in 1609, and in 1799, Russian sailors who died of an infectious disease were buried there.
Several islands were fortified over the centuries. Inchcolm was raided by English troops during the 14th century Wars of Independence. In the 16th century, Inchkeith, Inchcolm and Inchgarvie all suffered English occupation. The Earl of Somerset garrisoned the islands in 1547 after the Battle of Pinkie Cleugh, building a large square fort on Inchkeith. His forces, mainly Italian mercenaries, were ejected by a combined Franco-Scottish force in 1549. Only Inchcolm was fortified during the Napoleonic wars. Inchkeith was fortified in 1880, and Inchgarvie was armed early in the 20th century. During the First and Second World Wars, Inchmickery, Inchcolm and Cramond Island formed part of a defensive line of guns covering anti-submarine booms across the river.
Many of the islands have ecclesiastical associations. The Isle of May has a long history of ecclesiastical activity, including a 13th-century Benedictine church. St Adrian of May was murdered there by invading Danes in 870. The scientific name of the northern gannet, Morus bassanus, was chosen in recognition of this bird's connection with the Bass Rock.
Reader's Guide
The Islands of the Forth are significant for their varied geology, history, and natural history. Geologically, most are remnants of igneous intrusions, with the Bass Rock being a phonolite volcanic plug and Craigleith a laccolith of essexite used for curling stones. The islands have been sites of ecclesiastical activity, military fortifications, and unusual historical experiments, such as the 1493 language experiment on Inchkeith. The Firth of Forth is an important area for nature conservation, hosting diverse bird and sea life. The Bass Rock is the world's largest single rock gannetry, with over 150,000 nesting northern gannets. Other islands support significant seabird colonies, and the inner Firth is important for wintering wildfowl and wading birds. The islands also have a history of human habitation, though only Inchcolm has had a resident population in recent years. The area's natural and historical features make it a notable location for both conservation and historical study.
Did You Know?
- The scientific name of the northern gannet, Morus bassanus, is derived from the Bass Rock.
- In 1493, King James IV directed a dumb woman and two infants be transported to Inchkeith to see what language they would speak; some said they spoke good Hebrew.
- The Bass Rock has more than 150,000 nesting northern gannets, and their droppings give off 152 tonnes of ammonia per year.
- Craigleith was historically used as a rabbit warren, but the rabbits were wiped out by myxomatosis in the 1950s.
Frequently Asked Questions
What are the Islands of the Forth and where are they located?
The Islands of the Forth are a small cluster of islands scattered across the Firth of Forth and the River Forth estuary on Scotland's east coast. Most lie in the open water between the Lothians and Fife, just east of Edinburgh, with a couple sitting further west in the estuary itself.
What is the geology of the Islands of the Forth?
Geologically, the islands are largely the exposed tips of ancient igneous intrusions. Their rock types include basalt, phonolite, essexite, dolerite, picrite, and trachyte, giving each island a distinct mineral character.
What makes Bass Rock especially famous among the Islands of the Forth?
Bass Rock hosts more than 150,000 nesting northern gannets, making it the largest single rock gannetry on the planet. The sheer density of seabirds there draws ornithologists and birdwatchers from around the world every summer.
Are there permanent human residents on any of the Islands of the Forth?
Only one island—Inchcolm—still has people living there year-round. The rest are unoccupied, though they have long served as lighthouse stations, military outposts, and former religious sites.
What historical roles have the Islands of the Forth played over the centuries?
Over the centuries the islands have doubled as monastic and religious settlements, coastal fortifications, and navigation aids. At least one lighthouse or light on the skerries dates back to the 1600s, and the area remains an important stop for maritime traffic through the firth.
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