Landscape evolution models are generally driven by erosion from water flowing over the land’s surface, due to an energy gradient inherited from (and resulting in) topography. Young volcanic terranes are typically characterized by extensive lava fields having some topographic relief but little or no fluvial dissection. In these landscapes, development of drainage networks is fundamentally limited by the very high permeability of the rocks, resulting in virtually all precipitation infiltrating the surface and contributing to deep groundwater. In the absence of surface runoff, drainage networks develop extremely slowly and by different suites of processes than in landscapes where surface and shallow sub-surface flow prevail. Mechanisms and rates associated with these weathering processes are poorly understood, and likely to vary by climatic and geomorphic setting.

This quarter we will explore the development of drainage networks on porous lava flows, drawing from examples in the Oregon Cascades, Jordan, Libya, Hawaii, the Galapagos and other areas we would like to go on field trips.

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