Pebbles on the beach

Beach Stones at Crabby Bay

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The colours, patterns and textures of the beach stones at Crabby Bay on Alderney in the Channel Islands reflect the ancient geological composition of the island. The three main rock types on the island are diorite, foliated quartz-diorite or granodiorite with gneiss of Alderney type, and Alderney sandstone, all of which are probably Precambrian of Pentrevian age dating from between 2000 and 2500 million years ago! Multiple volcanic intrusions penetrated the rocks at a later date. There are some modern inclusions, and some pebbles could well be dumped ships’ ballast.

4 Replies to “Beach Stones at Crabby Bay”

  1. Yes, Crabby Bay is just around the corner from the harbour. There is a lot of made ground with hard core from all sorts of sources in the area so I guess some of it is bound to end up rolling around on the beach.

    Liked by 1 person

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