galston gorge is a valley located in the berowra valley regional park in sydney, australia. it separates galston from hornsby heights, and is intersected by galston road and the heritage-listed tunks creek bridge at the foot of the valley. adjacent to tunks creek bridge, there is a second concrete bridge that crosses berowra creek. the gorge itself contains many walking tracks, waterfalls and a variety of australian flora, and is a popular spot for hikers, cyclists and rock climbers.