Keys to gully formation processes on Mars: Relation to climate cycles and sources of meltwater

Advances in dating gullies on Mars using superposition relationships and a stratigraphic marker horizon link gully chronostratigraphy to recent climate cycles. New observations of gully morphology show the close association of gully source regions, channels, and fan deposits with well-documented ice-rich latitude-dependent mantle deposits, the deposition of which is interpreted to be coincident with recent ice ages. On the basis of these close correlations, we interpret the formative processes for mid-latitude gullies to involve melting of these ice-rich mantling deposits and the generation of an aqueous phase leading to fluvial activity. Continued monitoring of gullies by spacecraft in the current interglacial climate period (similar to 0.4 Ma to the present) will permit assessment of changing rates and styles of gully activity in the now largely depleted source areas. (C) 2011 Elsevier Inc. All rights reserved.