The phenomenon known as ice pancakes spotted on Ullapool River in the Highlands.
An amateur photographer has captured unusual ice formations in the north of Scotland.
Andy Williams snapped the images of ice which had frozen in a flat, round shape on the Ullapool River in the Highlands at the weekend.
Called pancake ice, the phenomenon is usually seen only in the Arctic or Baltic Sea.
It is often caused by swirling foam floating on a river starting to freeze, usually overnight.
Andy, who works as a freelance marine biologist specialising in sea birds, spotted the pancake ice while out doing a bird survey.