Rockfall and rock avalanches are common in steep terrain on Earth and potentially on other planetary bodies such as the Moon and Mars. Since impacting rocks can damage exposed bedrock as they roll and bounce downhill, rockfall might be an important erosive agent in steep landscapes, even in the absence of water. We developed a new theory for rockfall-driven bedrock abrasion using the ballistic trajectories of rocks transported under gravity. We calibrated this theory using laboratory experiments of rockfall over an inclined bedrock simulant. Both the experiments and the model demonstrate that bedrock hillslopes can be abraded by dry rockfall, even at gradients below the angle of repose, depending on the bedrock roughness. Feedback between abrasion and topographic steering of rockfall can produce channel-like forms, such as bedrock chutes, in the absence of water. Particle size has a dominant influence on abrasion rates and runout distances, while the hillslope angle has a comparatively minor influence. Rockfall transport is sensitive to bedrock roughness; terrain with high friction angles can trap rocks creating patches of rock cover that affect subsequent rockfall pathways. Our results suggest that dry rockfall can play an important role in eroding and channelizing steep, rocky terrain on Earth and other planets, such as crater degradation on the Moon and Mars.

中文翻译：

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落石切割基岩和渠道化的机理模型与实验

落石和岩崩在地球陡峭的地形中很常见，也可能在月球和火星等其他行星体上发生。由于冲击岩石在向下滚动和弹跳时会损坏裸露的基岩，因此即使在没有水的情况下，落石也可能是陡峭景观中的重要侵蚀剂。我们利用重力作用下岩石的弹道轨迹，开发了一种落石驱动的基岩磨损的新理论。我们使用倾斜基岩模拟物上的落石实验室实验校准了这一理论。实验和模型都表明，基岩山坡可能会被干燥落石磨损，甚至在低于休止角的梯度下也是如此，具体取决于基岩粗糙度。在没有水的情况下，落石的磨损和地形转向之间的反馈可以产生类似通道的形状，例如基岩滑槽。颗粒尺寸对磨损率和跳动距离具有主要影响，而山坡角度的影响相对较小。落石输送对基岩粗糙度很敏感；具有高摩擦角的地形可能会困住岩石，形成岩石覆盖斑块，影响随后的落石路径。我们的研究结果表明，干燥的落石在侵蚀和疏导地球和其他行星上陡峭的岩石地形方面发挥着重要作用，例如月球和火星上的陨石坑退化。