Edited sentence: Recent basaltic volcanic activity has produced many volcanic cones throughout the Auckland Region, including the iconic island of Rangitoto.The Auckland Region is built upon a basement of Greywacke Rocks, that form the form many islands in the Hauraki Gulf, the Hunua Ranges, and land to the South of Port Waikato.The Waitakere Ranges to the West represent the remains of an andesitic volcanic arc.The main isthmus and North Shore are composed of Waitemata sandstone and mudstone