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Historically, geomorphologists have applied uniformitarian principles based on a temperate normality to all water-worn landscapes. Isolation of tropical landforms within formal morphogenetic regions, which arose during the early history of the subject, has persisted. However, in a global geomorphology, plate tectonic motion, Milankovich cycles of climate change and invasive weather systems all render fixed climatic boundaries meaningless and, on every timescale of enquiry, interaction of the tropics with extra-tropical regions is fundamental. In tropical regions, the continuity of weathering processes through geologic time emphasizes their contemporary relevance and, with knowledge of Quaternary climate changes, increases understanding of the nature of landscape sensitivity and instability and fluvial sedimentation on millennial timescales. Examples are illustrated from northeast Queensland, Australia and northwest Kalimantan, Indonesia. Global concerns centred on hazards and resources need to be addressed through a reciprocal exchange of ideas involving greater focus on tropical areas. [ABSTRACT FROM AUTHOR]

The article comments on theoretical issues addressed by Michael F. Thomas in his article "Lessons From the Tropics for a Global Geomorphology." It is noted that the discussion of Thomas on the historical markers of tropical geomorphology skillfully portrays its evolution in space and time. Thomas has also pointed out that the dynamics of the globe involve fluxes of energy and interactions among all elements.

The article comments on theoretical issues addressed by Michael F. Thomas in his article "Lessons From the Tropics for a Global Geomorphology." It is argued that there is much to learn from the interactions between biological processes and geomorphological processes that are apparent in tropical environments. The challenge for global geomorphology is to scale up from the local effects and processes to a more general unified theory of landscape dynamics and evolution.