COLLABORATIVE RESEARCH: Relief Evolution at the Fluvial-Glacial Transition

[9980465]大多数中纬度和高纬度的山脉都受到冰川侵蚀的显著影响。高山地形中孤立的尖顶、狭窄的山脊、长长的光秃秃的岩石山坡和宽阔的山谷，立即给人一种定性的印象，即冰川是高效的腐蚀剂，冰川侵蚀产生了相当大的起伏。然而，关于冰川侵蚀的速率和模式、控制它们的因素，甚至从河流（非冰川）侵蚀向冰川侵蚀转变的形态学后果，我们所知甚少。我们建议利用冰川南缘的自然实验室，在那里可以研究相邻的、部分的和未冰川的，但其他方面相似的盆地。我们确定了加利福尼亚州内华达山脉东部和科罗拉多州圣克里斯多山脉北部的两个野外环境，在那里可以定量地估计冰川侵蚀单独引起的地形变化的数量和模式，作为冰川作用强度的函数。我们提出了一项研究计划，结合野外测绘、DEM分析和宇宙成因同位素定年，在这两个野外环境中定量检验在冰川地貌和侵蚀的初步调查中提出的5个假设

9980465WhippleMost mid- and high-latitude mountain ranges have been sculpted dramaticallyby glacial erosion. The isolated spires, narrow ridges, long bare-rockhillslopes, and broad valleys of alpine terrain immediately give aqualitative impression that glaciers are highly efficient erosive agentsand that glacial erosion produces considerable relief. However, little isknown quantitatively about the rates and patterns of glacial erosion, thefactors that control them, nor even the morphological consequences of ashift from fluvial (non-glacial) to glacial erosion. We propose to exploitnatural laboratories at the southern limit of glaciation where adjacentfully-, partially-, and un-glaciated, but otherwise similar, basins can bestudied. We identify two field settings in the eastern Sierra Nevada,California, and the northern Sangre de Cristo range, Colorado, where onemay estimate quantitatively the amount and pattern of topographic changeattributable to glacial erosion alone as a function of the intensity ofglaciation. We propose a research program in these two field settingscombining field mapping, DEM analysis, and cosmogenic isotope dating totest quantitatively 5 hypotheses developed during a preliminaryinvestigation of glacial landforms and erosion