Quartz is the main type of rock that make up the outer banks. Quartz is an igneous rock that was formed 10 million years ago when it becomes crystals from molten magma. Quartz is very resistant to erosion but the outer banks are going to get smaller over time because of erosion.
There is no guarenteed way that the outer banks were formed, but the main theory is that the islands formed when waves stirred sediment up from the sea floor. Over many years sand formed and sand bars occured making this landmark.
The outer banks have changed over time because of erosion. Erosion has caused the islands to become smaller over the years. This type of erosion is called coastel erosion, where sediment and rocks is slowly removed by water and leads to loss of land and retreating of the coastline. The future of the banks are not looking good. They have already lost 3000 feet worth of land in widthin the past century. Rising sea levels and beach erosion are harming houses and buildings. The erosion conditions are supposed to worsen over time as well as sea levels rising, so in the future, there will not be much of the outer banks left.