This small but high relief physiographic province (Figure 3.5) separates the Coastal Plain of southeastern Thailand from the southern plains of the Mekong River.
The northern part of this hilly region is known as the Cardamom Hills, and the southern part, the Elephant Hills.
The hills also encircle a small patch of coastal plain in cambodia.
Within half a kilometre or the sea, the hills to rice very sleeply and an elevotion of 1000 m is reached in less than 10 km.
The highest peak is slightly over 1700 m. Hills are flat-topped and steep-sided, with small structure-guided streams flowing wesward in narrow gorge-like valleys.
In their lower courses these streams follow a meandering course through the contrast, the hills slope much more gently to the northeast, towards the Tonle Sap area.
The local streams are also longer and flow over a gentler gradient.