 Erosion by wind, rain, storms and ice over millions of years carved out the plateaus of the Northern Tablelands, and rivers and streams gradually cut back the eastern edge of the tableland creating deep gorges that eventually formed one continuous escarpment.The jagged scarp is slowly retreating west and this movement can be seen today in the erosion of steep cliffs at places like Wollomombi, Dangars and Apsley Gorges.The Apsley Macleay Gorges are a converging point for moister eastern coastal and dry western floras, and some 950 native plant species have been identified, of which 36 are rare or threatened.