第四紀地層對比之研究: 生物地層:化石帶不明顯 岩性地層:局部而受控於沈積環境 時間地層:值得一試 定年法之限制: 一、不同材料 14C:漂木,貝類 FT :火成岩 TL,ESR:沈積物,貝類 二、不同年限
河階之定年: 新地體構造特性 河流下切速率 定年方法: (1)14C:採樣不容易 適用年限短 (2)TL,ESR:採樣不容易 (3)?
Application of the Diffusion Model in Slope Evolution Journal of the Geological Society of China 35(4), 407-419.
Morphological Dating Down wearing and decrease of slope angles through time Maintenance of steep angles and parallel retreat of slope segments.
Diffusion Model (linear) Assumptions Material conservation Material homogeneous Mass transport rate = m
k = erosion constant or diffusivity
The rate of change in elevation (dy/dt)at a point on a hillslope is proportional to the curvature (d2y/dx2).
Simulation of Poly-cyclic Terraces Once the terrace scarps are formed, the slope evolves due to the lateral erosion of river at the bottom and direct erosion on the slope surface.
Mid-section Maximum-Slope-Angle (MSA) MSA decreases non-linearly with the diffusivity and t, kt. MSA decreases more rapidly with a larger diffusivity.
Diffusivity is a function of lithology and climate, indicating its various in different places and time duration. Diffusivity can be derived by terrace with known age. Ex: Tahan river. LT, 90 m2/ka; FT, 10 m2/ka Diffusivity has a linear relationship with the height
Simulation of the Active Fault Scarp