The Pinosuk Association occurs between Mt. Kinabalu and Ranau, and includes both the Pinosuk Plateau, a piedmont feature with gentle slopes, and the deeply dissected slopes between the plateau and Sungai Liwagu.
Parent materials consist of poorly consolidated, unsorted gravel in a sandy to clayey matrix, and are considered to be solifluction deposits. These deposits overlie sandstone and mudstone, which are exposed in some valley sides and gorges. terraces of alluvium probably derieved from the solifluction deposits also occur in these valleys.