Half Dome

Another very famous structure in Yosemite is called half dome. Half dome is a unique granite structure. True to its name, Half Dome looks like a round granite hill, chopped off on one side of the hill, creating a half dome. Despite its name, half dome was never a full dome. Millions of years ago, at the same time El Capitan was formed, half dome was about 20% bigger than it is today. Differing joints in the rock formation led to this unique formation. Deep insid the granite rock, wide verticle cracks were exposed from glaciers that undercut half domes base and carried about 20% of the formation away. This erosions and later rock falls left the verticle face as steep as we see it today. The more "dome" looking side is formed due to different types of joints called exfoliation joint. These joints are surface parallel fracture systems in the rock that lead to the specific type of erosion seen on the dome part of half dome.