Howth village and harbour area. It comprises the main island, a range of sea stacks and rocks and a grassy islet, (the) Thulla. The Eye lies 1,200–1,500 metres from Howth Harbour and around 13 km from Dublin city centre. The main island is roughly triangular, the points lying to the northwest, northeast and south, and around 600–700 metres along the edges. The terrain slopes broadly downhill from north to south, and to some extent from northeast to southwest. The most prominent feature is a sea stack called "the Steer", at the northwestern corner of the island, while at the northeastern point is a group of rocks or small sea stacks known as "the Stags". Closer to the Steer than the Stags on the northern coast is Seal's Cave, one of several sea caves. On the south-southwestern face of the island is Carrigeen Bay, with a sandy beach, and above that a shingle beach. Linked by a line of shelving rocks, exposed at low tide ("drying rocks"), the grass-surfaced islet of Thulla lies south of the main island, and the Rowan Rocks to the southeast and east of cliffs on the eastern aspect of the Eye. Also on the eastern coast are two inlets, Samper Hole nearer the Stags, and the longer and narrow Long Hole just north of the rocks linking the main island to Thulla. Between the island and Baldoyle Spit off Portmarnock Point is Howth Sound, and to the southwest the channel between the island and Howth Harbour, while in all other directions open sea extends for kilometres. The main island has sea-level coast on the western side, but on the east cliffs are 10s of metres high, while the island's highest point is about 69m above sea level. In total, there are just over 2.5 kilometres of cliff. Thulla is at most two metres above the water. Geology, hydrology and climate Ireland's Eye and its associated rocks are formed from Cambrian quartzite and greywacke, notably visible in the steep cliffs on the northern and eastern faces of the main island. The visible sections display faulting and folding. The island, and Howth Head, lie at the northern end of the Bray geological series. Three lithostratic groups exist in the bedrock of the island, being, south-to-north, the Thulla Formation, the Carrigeen Formation and the Steer Formation; these have parallels in three of the five formations comprising the bedrock of