Laws, place, history and the interpretation of landforms

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The state of an Earth surface system (ESS) is determined by three sets of factors: laws, place, and history. Laws (L = L1, L2, …, Ln) are the n general principles applicable to any such system at any time. Place factors (P= P1,P2,…, Pm) are the m relevant characteristics of the local or regional environment. History factors (H= H1, H2, …, Hq) include the previous evolutionary pathway of the ESS, its stage of development, past disturbance, and initial conditions. Geoscience investigation may focus on laws, place, or history, but ultimately all three are necessary to understand and explain ESS. The LPH triad is useful as a pedagogical device, illustrated here via application to explaining the world's longest cave (Mammoth Cave, KY). Beyond providing a useful checklist, the LPH framework provides analytical traction to some difficult research problems. For example, studies of the avulsions of three southeast Texas rivers showed substantial differences in avulsion regimes and resulting alluvial morphology, despite the proximity and superficial similarity of the systems. Avulsions are governed by the same laws in all cases [L(A) =L(B) =L(C)], and the three rivers have undergone the same sea-level, climate, and tectonic histories, as well as the same general anthropic impacts [H(A) ≈H(B) ≈H(C)]. Though regional environmental controls are similar, local details such as the location of the modern main channel relative to Pleistocene meander channels differ, and thus these place factors explain the differences between the rivers. The LPH framework, or similar types of reasoning, is implicit in many types of geoscience analysis. Explicit attention to the triad can help solve or address many specific problems and remind us of the importance of all three sets of factors. Copyright © 2016 John Wiley & Sons, Ltd.

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