:Cyrn Formation

{{Use dmy dates|date=April 2022}}

{{Infobox rockunit

| name = Cyrn Formation

| image =

| caption =

| type = Formation

| age = Ordovician

| period = Ordovician

| prilithology =

| otherlithology =

| namedfor =

| namedby =

| region = Wales

| country = {{UK}}

| coordinates =

| unitof =

| subunits =

| underlies =

| overlies =

| thickness =

| extent =

| area =

| map =

| map_caption =

}}

The Cyrn Formation is a geologic formation in Wales. It preserves fossils dating back to the Ordovician period.