Ictis Insula (St Michael's Mount)

Port and Settlement

St. Michael’s Mount was widely known as a port and trading market from very early times. Prehistoric traders passing between the western parts of Britain and the Continent would not have wished to risk the rough and dangerous voyage around Land’s End, and so sent their cargoes across the narrowest and most level part of Cornwall from the Hayle estuary to St. Michael’s Mount.

By the first century BC, the dominant traders at St Michael’s Mount were the Veneti tribe from Southern Brittany. In 56 BC they fought and lost a major sea battle with Roman forces under Julius Caesar which, coupled with the Roman invasion of Britain in AD 43, probably ended this lucrative trade at St Michael’s Mount.

Archaeological finds on St Michael’s Mount

In 1995 an archaeological watching brief of a sewer trench found Later Iron Age pottery, of the Ictis period, and its distribution drew attention to a group of six possible round house platforms – perhaps the site of Ictis itself – on the south-eastern slopes of the Mount. A Neolithic flint arrowhead (circa 3500 B.C.) was also found, adding some support to the suggestion that somewhere as dramatic as the Mount, whether rising from sea or forest, would have been from earliest times a central place of authority similar to Carn Brea, the Neolithic hill-top enclosure near Redruth.

Classical References to St Michael’s Mount / Ictis

While Ictis is widely accepted to have been an island somewhere off the southern coast of what is now England, scholars continue to debate its precise location. Candidates include St Michael’s Mount and Looe Island off the coast of Cornwall, the Mount Batten peninsula in Devon, and the Isle of Wight further to the east.

Ictis, or Iktin, is or was an island described as a tin trading centre in the Bibliotheca historica of the Sicilian-Greek historian Diodorus Siculus, writing in the first century BC.

Towards the end of the fourth century B.C., shortly after the death of Alexander the Great, Pytheas, a Greek geographer from Marseilles, had made a voyage of exploration round the coast of Britain looking for the source of amber in the Baltic. Unfortunately, the records of his voyage were lost but they were known to later classical writers such as Timaeus, Posidonius and Pliny. The evidence of these writings is vague and conflicting but represents all that was known about the tin trade in the ancient classical world.

In particular, Diodorus, a Sicilian Greek historian, writing in the first quarter of the first century A. D., gives an account which is probably a description of the working of Cornish tin (by streaming from the rocks) about the time of the voyage of Pytheas, and how it was carried over to St. Michael’s Mount. The inhabitants of that part of Britain which is called Belerion [that is to say Land’s End],” Diodorus says, “are very fond of strangers and from their intercourse with foreign merchants are civilised in their manner of life. They prepare the tin, working very carefully the earth in which it is produced. The ground is rocky but it contains earthy veins, the produce of which is ground down, smelted and purified. They beat the metal into masses shaped like astralgi [knuckle-bones] and carry it off to a certain island off Britain called Ictis. During the ebb of the tide the intervening space is left dry and they carry over to the island the tin in abundance in their wagons.” In a later passage in the same context ~Diodorus says, “Here then the merchants buy the tin from the natives and carry it over to Gaul, and after travelling overland for about thirty days, they finally bring their loads on horses to the mouth of the Rhone.” Diodorus mentioned both Marseilles and Narbonne by name as places to which Cornish tin was sent on the Mediterranean coast.

Ireland was rich in gold and copper, and the Irish traders would have found transport by sea much simpler than the journey along the tracks through the almost impassable forests and swamps of England and Wales. Dr. H. O’Neil Hencken in his book Archaeology of Cornwall and Scilly, published in 1932, suggested that by the Iron Age the island of St. Michael’s Mount would have become a highly important port.

St. Michael’s Mount, the trading station of the ancients,” Dr. Hencken wrote, “rises from Mount’s Bay in full view of the early tin streamers’ forts and villages.” However, he pointed out that it must be admitted that not many signs of the rather advanced civilisation of the foreign merchants have come down to us.

One of the main difficulties of identifying St. Michael’s Mount with the island of Ictis was the legend that St. Michael’s Mount was within historic memory five or six miles inland from the sea in the middle of a dense forest. When William of Worcester visited the Mount in 1478 he recorded that it was formerly called “the Hore-Rock in the wood”. Also the old Cornish name for the Mount meant “the grey rock in the forest”. However, Sir Gavin de Beer, F.R.S., a former Director of the Natural History Museum, wrote in his book Reflections of A Darwinian, published in 1962, that scientific methods of analysing the traces of old tree trunks still found in Mount’s Bay had indicated that the forest was submerged by the sea at least 1, 500 years before Pytheas came there on his voyage of exploration in about 325 B.C.

The most likely alternative to St. Michael’s Mount as the island of Ictis was the Isle of Wight, the Roman name of which was Vectis, but Sir Gavin de Beer suggested that it had not been possible to cross to the Isle of Wight by foot from the mainland since the days of neolithic man. Also it is most unlikely that Cornish tin should have been carried so far to the port of embarkation. Canon Taylor in his History of St. Michael’s Mount suggests that William of Worcester may have confused the English St. Michael’s Mount with Mont St. Michel on the coast of Normandy and that the “Hore-Rock in the wood”, referred to the French and not to the English Mount. It is improbable that the merchants who bought the tin at St. Michaels Mount were Phoenicians or Carthaginians.

Probably the tin was shipped to Gaul by the Veneti, a powerful sea-faring people who inhabited Southern Brittany. The Veneti had close linguistic and cultural contacts with Cornwall. Their ships were described by Julius Caesar who fought a naval battle with them in 56 B.C. They were built solidly of oak with high prows and leather brown sails. Julius Caesar was the last classical writer to mention Cornish tin, probably because the tin trade was ended by the defeat of the Veneti and the Romans had discovered the other sources of tin in Spain.

Roman Milestones from South-West Cornwall

RIB 2233 - Milestone of Constantine I

For the Emperor Caesar Flavius Valerius Constantinus Pius, most noble Caesar, son of the deified Constantius Pius Felix Augustus.


Constantine I, middle of a.d. 306-spring 307; Huebner wrongly assigns it to Constantinus II (A.D. 337)

RIB 2232 - Milestone of Postumus

For the Emperor Caesar, our Lord, Marcus Cassianius [Latinus Postumus ..

IMP [...]

Postumus, A.D. 258-68. Cf. the milestones RIB 2255, 2260.

References for Ictis Insvla

  • St Michael’s Mount – Illustrated History and Guide by John St. Aubyn (Cornwall, 1978);
  • The Roman Inscriptions of Britain by R.G. Collingwood and R.P. Wright (Oxford 1965). 

Map References for Ictis Insvla

NGRef: SW 515 299 OSMap: LR203, Explorer7

Roman Roads near Ictis Insvla

Probable Road/Trackway: ENE (13) to Carn Brea (Carn Brea, Cornwall) Probable Native Trackway: W (8) to Carn Evny (Cornwall) Probable Native Trackway: NW (5) to Chysavster (Cornwall)

Sites near Ictis Insula (St Michael's Mount)