坡立谷又称岩溶盆地或岩溶平原，指喀斯特区宽阔而平坦的谷地。谷地两侧多被峰林夹峙，谷坡急陡，但谷底平坦，横剖面如槽形。谷地内常有过境河穿过，由谷地一端流出，至另一端潜入地下。在河流作用下，谷地迅速扩大，堆积了较厚层的冲积物。此外，还保留着石灰岩残积红土以及低矮的石灰岩孤峰或残丘。

Polje, also known as karst basin or karst plain, refers to the wide and flat valley in karst areas. The two sides of the valley are often imbedded by the peak forest, with steep brae , flat valley and sulciform cross section . There is often a passing river running through the valley from one side to the other side and dive into the underground. Under the action of rivers, the valley expands rapidly, accumulating thicker alluvial deposits. In addition, there also reserved residual limestone eluvial laterite and low limestone peaks or residual hills.