The coast is about from Lizard Point to Gwennap Head. Heading north and west from Lizard Point, the serpentine and hornblende schist cliffs reach a maximum height of 71 m (233 ft) at Vellan Head and are only broken by small streams and coves such as at Kynance, Gew-grade and Mullion Cove. After Gunwalloe Fishing Cove the cliffs have the softer look of Devonian Meneage Formations of greywacke and mélange, with erosion a problem either side of the naturally dammed ria of Loe Pool. West of Porthleven there are high Devonian slate and granite cliffs to Rinsey Head after which the cliffs are topped by Pleistocene periglacial head and have eroded to form sandy beaches such as those at Praa Sands and Kenneggy. These beaches are in deficit and the cliff line is retreating. With the exception of the harder Devonian dolerite and gabbro of Cudden Point, the low, eroding cliffs and beaches continue to Mousehole. This part of the bay is the most populated with the towns of Penzance and Marazion and the villages of Newlyn and Mousehole. Beyond Mousehole the granite cliffs, rise to 60 m, and are broken by small streams such as at Lamorna Cove and Penberth.