When the winter causes the climate cool down in mountainous regions, rainfall begins to come down in the form of snow. The snow piles up on top of old layers of ice that have not melted during the summer on the high mountain peaks. As the snow accumulates at a greater rate than it melts, the ice layer on the mountain peak grows thicker every year. Finally, the weight of the snow compresses the lowest layers into ice. Slowly, the ice begins to move down the slope of the mountain, accelerated by water from melting snow. 

As the ice moves down the slope of a mountain, it can accumulate crushed rock materials and carry them down with itself. Rock material that has been carried by ice from one place to another is referred to as glacial till. 

When ice moves down the slope, it and the glacial till it carries erode the slope of the mountain. This results in the formation of smooth glaciated rock and U-shaped valleys. 

Glaciated rock is common in Finland. It has been smoothed down by glacial movement.​