Shi Men Valley Glacial Ridge is located within the Stone Gate U -Valley. It is a sandstone ridge formed during glaciation movements. This ridge blocked the flow of ice，creating a firn – basin. There is a concave wind recess on the windy side (west) of the ridge called, “wind mouth ”. There is another recess in the south where water flew, called, “water mouth”. This ridge is a classic example of a glacial ridge.