Fjord is a term used in geomorphology to define a huge valley formed by rocks and flooded with water, due to the melting of ice in the Ice Age.
The word fjord or fjord is of Norwegian origin (fjord) and means "safe harbor", because the waters of the fjords are normally calm, ideal for fishing or mooring boats.
The dimensions of the fjords are incredible, reaching 350 kilometers in length and walls over a thousand meters high, up to 1,500 meters deep.
You biggest fjords in the world are located in North America (Canada and Alaska), Norway, Switzerland and Chile. Among the main and best known are the fjords of Milford Sound, O Geiranger fjord, Oslo fjord and Naeroy fjord.
These gigantic, salt-water valleys formed millions of years ago during the Ice Ages. Due to the low average temperature of the planet at that time, the great ice sheets were advancing on the warmer regions of the Earth, dragging everything in front of it, including pieces of rocks. This is called "glacial erosion".
As the Earth's atmosphere warmed, the immense blocks of ice receded, giving way to long and deep water paths through the rocks.
Many people confuse fjords with rias, however they are quite different. While the fjords are tens of meters deep, the rias don't even come close. Another difference is in the shape: the fjords have a "U" shape, whereas the rias resemble a "V".