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Natural History of Scilly

Collage of wildlife, rock formations and aerial view of islands

 The geology and wildlife of Scilly - referenced notes on rocks, animals and plants

  • what to look for

  • where to look

  • how and when it arrived in the islands   

  • a geological tour of the islands 

  • the story of Scilly's 'St Martins Ant'

  • the Scilly Shrew puzzle

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And external links to

  • identification keys

  • species lists

  • submitting wildlife records

  • reporting whale and dolphin strandings

  • citizen science projects


The group of Islands we see today began as a massive mound of molten rock that rose up under the edge of the Old Red Sandstone continent 290 million years ago. Much has changed since then! Most of the geological features in Scilly are either associated with the granite bedrock or with much more recent events in the Ice Ages and some of these geological features are the best examples of their kind in Europe!

As the geography changed over the millennia, so did the flora and fauna. Towards the end of the last Ice Age, rising sea levels cut the Scillonian land mass off from Britain and continental Europe. Some species were unable to interbreed with the European populations so they changed gradually, giving rise to 'endemic' plants and animals unique to the islands.


Although the current landmass of Scilly is tiny, the islands offer a wide range of habitats which provide food and shelter for a rich mixture of native, endemic, introduced, migrant and vagrant species.


  • Events shaping the geology of Scilly

  • Origins of the granite bedrock

  • Intrusions and minerals

  • Glacial deposits

  • Geological tour

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  • What makes Scilly special for wildlife

  • Rare and unusual animals and plants

  • Life cycles and migration patterns

  • Timeline of arrivals and introductions 

Ant Forensics

  • The St Martins Ant mystery
  • How DNA sequence can help
  • Ant DNA and evolutionary tree
  • The mystery solved!