The road that divided the valley
Glen of the Downs
The Glen of the Downs was designated a National Nature Reserve in 1980 to protect its ancient semi-natural oak woodland. When the National Roads Authority proposed widening the N11 through the glen in the late 1990s, a group of protesters occupied trees in the reserve for two years (1997-1999) to obstruct the works. The road was widened regardless; the reserve survived in its current 59-hectare form. The woodland is an SSSI (Site of Special Scientific Interest) as well as an NNR. Sessile oak, ash, hazel, and an understorey of bluebell and wood anemone in spring.
Cambrian quartzite, 500 million years old
The Great Sugar Loaf
The Great Sugar Loaf (501m) is composed of Cambrian quartzite laid down approximately 500 million years ago. The quartzite was harder than the surrounding rocks; when the Pleistocene glaciers moved through north Wicklow, they eroded the softer material and left the Sugar Loaf's core standing. The cone shape is the result of freeze-thaw erosion on the exposed summit after the glaciers retreated. The scree visible on the upper slopes is still active - loose quartzite continues to break off the summit faces in winter frost.