The Jamison Valley stretches north-south from just outside Katoomba to the Mount Solitary ridge; in this direction it is approximately long. From west to east, it stretches from Narrow Neck Plateau to Kings Tableland, making it approximately wide. Like the entire Sydney and Blue Mountains region, the valley is a sandstone area, characterised by steep sandstone cliffs. Deeper into the soil there is a layer of shale, which is softer than the sandstone. As this layer of shale was eroded by the watercourses, it collapsed and brought the sandstone down with it, creating the characteristic sandstone valleys and canyons of the Blue Mountains, of which the Jamison Valley is one.