[4] The islands were left to the National Trust for Scotland by their previous owners, the highly important Celtic studies scholars John Lorne Campbell and Margaret Fay Shaw, in 1981, and are run as a farm and conservation area.

However, these initiatives have enjoyed only limited success, and in December 2017 it was announced that the trust would be devolving to the island community the responsibility for attracting and retaining new residents.

Within the lower half of the succession there are also coarse conglomerates deposited by rivers[16] The island is traversed by numerous normal faults most of which run broadly north–south.

Quaternary deposits include glacial till of limited extent around Tarbert and screes which are found beneath various of the small basalt cliffs.

Canna is noted for its tiers of basalt pillars that rise over the eastern half of the island and the sea cliffs that dominate its northern shore.

It is made of volcanic rock called tuff, and it has such a high iron content that the compass of nearby ships are distorted, pointing to the hill rather than north.

[4] Canna is littered with numerous pottery sherds evidencing the island's occupation in the Neolithic era, along with a small number of mysterious cellars dug into the ground.

Bronze Age remains are some of the most extensive in the North-Western Highlands, particularly at the western end of the island; these include fragments of huts arranged in circles, and ancient field walls, as well as pottery artefacts from the Beaker Culture.

In Gaelic the site is known as Sgorr nam Ban-naomha, meaning "grassy slope of the holy women"; in the 19th century, local people believed it had once been a nunnery,[22] but it is now thought to have been a hermitage, associated with the monastery at Keill.

[24][25] A number of large oblong arrangements of kerb-stones throughout the island are thought to possibly indicate Viking ship burials, based on the evidence of similar structures on the Isle of Arran (which was also part of Suðreyjar).

The Abbot, Dominicus, obtained papal authority to ban all nobility from setting foot on the island, but this wasn't respected, and Canna had to be temporarily abandoned.

In 1428, the Abbot wrote to the Pope requesting that he pronounce a general excommunication against anyone who harmed one of Canna's inhabitants, or damaged their property, claiming: "by reason of wars and other calamities in the past divers homicides, depredations and other ills were perpetrated, so that some strong men of the familiars of the Abbot and convent were slain by pirates and sea rovers, and divers farmers and inhabitants of the island were afraid to reside there".

In 1548, the Dean of the Isles, Donald Monro, conducted a survey of the Bishop's lands and churches, reporting that the island was a: "faire maine land, foure myle lange, inhabit and manurit, with paroche kirke in it, guid for corne, fishing and grassing, with a falcon nest in it, pertines to the Abbot of Colmkill[note 9]",[31] In 1561, the Bishop agreed to rent the island to the leader of Clan Ranald, a branch of the MacDonalds.

Lachlan - the MacLean leader - demanded that the Spanish supply him with 100 soldiers, as the price of their refuge, which he used to launch an attack against the Small Isles, in pursuance of the feud; Canna was "burned with fire".

In the following year, Donald MacDonald, the son of the Clan Ranald leader, married the Baronet's daughter, Janet, quelling any potential dispute over the island.

At some point in the late 17th century, a small prison (now called "Coroghon Castle") was constructed on the side of an isolated stack at Coroghon; it was described by Thomas Pennant in 1772 as "a lofty slender rock, that juts into the sea: on one side is a little tower, at a vast height above us, accessible by a narrow and horrible path[note 15]: it seems so small as scarce to be able to contain half a dozen people.

A decade later, Argyll's Rising caused the Earl's feudal authority to be forfeit, making Clan Ranald direct vassals of the king.

[37] In London, the Bailie was held prisoner, for having taken part in the rebellion, until the Indemnity Act was passed in 1747;[37] for his troubles, Campbell was made a Lieutenant General.

At the end of the 18th century, kelp harvesting became a major industry on Canna, as a result of the Napoleonic Wars limiting foreign supplies of certain minerals.

However, when the wars ended, foreign supplies became available again, and the kelp price duly collapsed, causing a recession; in 1821, several of the inhabitants of Canna chose to escape their poverty by emigrating to Canada[note 20].

The Clan Ranald leader was not exactly a spendthrift, meaning that the lack of income from his tenants drove him into debt; in 1827, he sold Canna to Donald MacNeil.

Thom carried out a programme of investment, including an oak pier, a footbridge to Sanday, and a Presbyterian Church, St Columba's (though the population remained mostly Roman Catholic).

Campbell's American-born wife and fellow folksong collector Margaret Fay Shaw, remained at Canna House until her own death in 2004, at the age of 101.

[39] In the following year a cull against brown rats was ordered, for they had hitherto been allowed to expand to enormous numbers, and now threatened rare Manx shearwaters and human health; Canna is now rat-free.

This is used by the Caledonian MacBrayne ferry, MV Lochnevis, which links Canna, and the neighbouring Small Isles of Rùm, Eigg and Muck, to the mainland port of Mallaig (2+1⁄2 hours away).

By the end of 2006 it was believed that Canna was rat-free and during that summer there was also an encouraging increase in the number of breeding puffins and razorbills; Manx shearwaters were nesting for the first time since 1997.

[47] The pests caused damage to archaeological monuments, such as an Iron Age mound and stone remains from the Clearances, as well as the islanders' vegetable gardens.

The centre is linked to the archive of Scottish Gaelic language, literature, and culture that was collected by literary scholar and former owner of Canna and Sanday, John Lorne Campbell.

In May 2020, the National Trust US Foundation reported that major renovations were underway at Canna House and its gardens; the facility was originally expected to reopen in 2021.