The role of bedrock erodibility in the topography and landscape evolution of the Appalachian Mountains

山脉在板块运动形成后，仍在大陆上徘徊很久。在侵蚀衰变过程中，这些逐渐减少的山脉受到气候、盆地动力学和构造更新等变化条件的影响，从而产生复杂的信号。控制这些景观演变的另一个因素是侵蚀基岩的物质特性，随着岩石的挖掘，这些物质特性会随着时间的推移而变化。在许多古老的山脉中，地形和岩石类型之间存在相关性，包括在阿巴拉契亚山脉，这种现象的类型所在地。在阿巴拉契亚山脉的沉积岩中，基岩性质的作用至少在定性上是清楚的，但在变质岩中，这种关系就比较模糊了。这次调查的目的是确定高蓝岭的变质岩对景观的控制程度，并具体量化是什么使它们经久耐用。这将有助于了解阿巴拉契亚景观的起源，以及控制古代被动边缘可蚀性的过程。该项目还支持在阿巴拉契亚一所农村中学（约350名学生/年）的八年级地球科学课程中开发和增加实地考察经验的项目，目前该学校的课程中没有实地考察。该项目的具体目标是测量弗吉尼亚州和北卡罗来纳州蓝岭复杂变质岩的基岩属性，包括岩石强度（例如，点载荷测试），不连续（例如，裂缝扫描线），矿物学，以及通过实验室测试（冷冻/解冻，加热/冷却，微波酸消化和湖泊测试）对化学和物理表面过程的敏感性。大量的数据收集工作（约150个地点，500个样本）将填补复杂蓝岭岩石类型材料特性的主要数据空白。将从自然和人为暴露中获取样本，并将与相对地形位置（即山脊和山峰与谷底）以及许多其他地貌指标进行比较。将对数据进行综合，以测试基岩对地形的控制程度，并最终将其纳入控制这种环境下长期可蚀性的模型。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Mountains linger on the continents long after they are built by tectonic motions. During their erosional decay, these diminishing mountains are subject to modification by changing conditions, including climate, basin dynamics, and renewed tectonics, resulting in complex signals. Another factor that controls the evolution of these landscapes is the material properties of the eroding bedrock, which change through time as rocks are exhumed. Correlations exist between topography and rock type in many ancient mountain ranges, including in the Appalachian Mountains, the type locality of this phenomenon. In sedimentary rocks of the Appalachians, the role of bedrock properties is at least qualitatively clear, but in metamorphic rocks the relationships are murkier. The purpose of this investigation is to determine the degree to which metamorphic rocks of the high Blue Ridge control the landscape and to quantify specifically what makes them durable. This will contribute to understanding of the origin of the Appalachian landscape, as well as to the processes that control erodibility along ancient passive margins. This project also supports a program for developing and adding a field experience as a required element for eighth grade Earth Science classes in a rural Appalachian middle school (~350 students/year), where currently no field trips are included in the curriculum. The specific goals of this project are to measure bedrock properties of complex metamorphic rock of the Virginia and North Carolina Blue Ridge, including rock strength (e.g., point-load testing), discontinuities (e.g., fracture scanlines), mineralogy, and sensitivity to chemical and physical surface processes via laboratory testing (freezing/thawing, heating/cooling, microwave acid digestion, and slake testing). A large data collection effort (~150 locations, 500 samples) will fill a major data gap for the material properties of complex Blue Ridge rock types. Samples will be acquired from both natural and anthropogenic exposures and will be compared to relative topographic position (i.e., ridges and peaks vs. valley bottoms) as well as a host of other geomorphic metrics. Data will be synthesized to test the degree to which bedrock controls topography and ultimately be integrated into a model of what controls long-term erodibility in this setting.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.