The Glass House Mountains are a series of steep-sided volcanic plugs which dominate the landscape of the Sunshine Coast Hinterland. According to the geosciences, they were formed of rhylite and trachtyte, lavas which hardened inside the vents of tertiary volcanoes that have been greatly reduced by about 25 million years of erosion

The highest hill is Mount Beerwah at 556 meters above sea level, but the most identifiable of all the hills is Mount Tibrogargan which from some directions appears to be a face staring out to sea.