Wikipedia
Stone-boat
A stone-boat is a type of sled (sledge) for moving heavy objects such as stones or hay bales. Originally they were for animal-powered transport used with horses or oxen to clear fields of stones and other uses and may still be used with animals or tractors today .
The device may look like a low-profile sled with timber runners or have a flat bottom of planks secured together to slide over soft ground or snow. Originally made of wood, metal versions exist with hinges.