在台灣，探討更新世晚期高位河階地形演育時，常受限於定年資料取得困難，而無法獲得一致的看法，造成階地對比上的困難。大安溪中游的高位紅土階地(lateritic terrace, LT)受到造構活動的影響，使得地形面傾動、階地抬升量不一，增加了對比的困難度。本研究在各主要的地形面上，採取了階地土壤樣本，透過土壤化育的觀點，比較各階地土壤的化育程度，作為階面相對年代對比的參考。研究成果顯示，在大安溪中游段階地土壤間，可依各土壤之化育程度分為兩群，此能進一步推論大安溪中游的高位階地，約可對比為兩階，較高位的TA-1、TA-3和TA-4、次高位的TA-2與TA-5，顯示大安溪中游各高位紅土階地主要在兩個時期內分別形成。

Lack of dating materials has caused controversy over the correlations of lateritic terraces and reconstructions of fluvial landform evolution in Taiwan. Alternative methods, such as relative dating based on correlating pedogenic degrees between soils on the terraces, could be a practicable solution for gauging the correlations in lateritic terraces. These correlations are complex and difficult to measure in the mid-reaches of the Taan river ,because the terraces were uplifted and deformed by tectonic active faults and folds. This work sampled on the lateric terraces in the mid-reaches of the Taan river, and determined the pedogenic degrees of the soils. Analytical results show that the pedogenic degrees of the soils on the terraces were grouped into two types, the higher pedogenic degree, (TA-1, TA-3, TA-4) and the lower pedogenic degree, (TA-2, TA-5), indicating that the Taan river experienced two primary incision events of since the late Pleistocene..