Mount Coonowrin (Crookneck) () is composed of alkali rhyolite. It has good examples of vertical columnar jointing and has caves. Timber and steel pitons left by climbers can be found, though the mountain is now closed to climbers. It is a habitat for the peregrine falcon. Mount Coonowrin is the second highest; however, public access to it has been prohibited since 1999 due to the danger of trachyte rock stability.