Millions of years ago Ireland was almost entirely covered in ice. It is thought that this happened on two separate occasions. Glaciers can be extremely effective in shaping the landscape of earth through erosion and deposition. The Dublin/Wicklow mountains provide some of the most important information about glaciation processes and landforms available. Glacial features such as U-shaped valleys and drumlins can be observed in the landscape. The mountains were formed hundreds of millions of years ago with some rocks dating back to 570 million years ago! The younger rocks in the mountains date back to 400 million years ago.
Glendalough Glendalough (The Valley of the Two Lakes) is the best example of a U-shaped valley in Ireland. It is best known for the two glacial lakes which occupy the U-shaped valleys which were carved out by the glaciers which once covered Ireland hundreds of millions of years ago. It is also a great example of a deciduous woodland biome with Irish flora and fauna on display in the area. Located in the Wicklow Mountains National Park the area has been preserved very well. It has since developed as a tourist site with a hotel, restaurants and visitor centres opening up. Tourists visit the region every year for its history as a monastic site and glacial features. See Functions of Glendalough and Glaciation in Wicklow for more information on these.