Iona Group

{{Infobox rockunit

| name = Iona Group

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| type = Group

| period = Tonian

| age = 1000–950 Ma

| prilithology = metasandstone

| otherlithology = metasiltstone, semipelite, mylonite, conglomerate

| namedfor = Iona

| namedby =

| region = Inner Hebrides

| country = Scotland

| coordinates =

| unitof = Wester Ross Supergroup

| subunits =

| underlies =

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| thickness = ~700 m

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The Iona Group is a sequence of metamorphosed Neoproterozoic sedimentary rocks that outcrop along the east coast of the island of Iona within the Inner Hebrides of Scotland. The name was given to this sequence by Stewart in 1969, keeping it distinct from the Torridonian, which it resembles. Since {{circa}} 2021, it has been assigned to the Wester Ross Supergroup.{{Cite journal |last=Krabbendam |first=M. |last2=Strachan |first2=R. |last3=Prave |first3=T. |date=2022 |title=A new stratigraphic framework for the early Neoproterozoic successions of Scotland |journal=Journal of the Geological Society |volume=179 |doi=10.1144/jgs2021-054|hdl=10023/24155 |hdl-access=free }}

Three divisions are recognised; i) interbedded metasandstones and metasiltstones, ii) slaty semipelites and iii) conglomerates, the clasts of which are largely metamorphic in origin. The rock strata are steeply inclined to vertical.{{cite web |title=Ross of Mull |url=http://www.largeimages.bgs.ac.uk/iip/mapsportal.html?id=1002386 |website=Geological maps portal |publisher=British Geological Survey |accessdate=1 March 2020}}{{cite web |title=Iona Group |url=http://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=IONA |website=The BGS Lexicon of Named Rock Units |publisher=British Geological Survey |accessdate=7 July 2021}}