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2008 Annual Science Report

University of California, Berkeley Reporting  |  JUL 2007 – JUN 2008

Landforms Made by Groundwater Discharge on Mars and Earth

Project Summary

On Mars and Earth, deep canyons with steep walls and no tributaries are found to terminate upstream in sharp amphitheater-shaped heads. For decades researchers have interpreted such features as being created by springs draining deep groundwater which undermine the head and advance it forward, with important implications for the history of climate on Mars. We have found through extensive field study of these features on Earth that such canyons are formed by waterfall erosion rather than by groundwater seepage. Hence, this morphology on Mars does not reliably indicate sustained groundwater discharge. This requires reconsideration of the interpretation of these features and of their significance as indicators of Mars environmental history.

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

In 2007 – 2008 our most important discovery is that Box Canyon, Idaho, our Mars analog site for seepage erosion, was instead carved by a large paleoflood about 45 thousand years ago (Lamb et al., Science, 2008). This finding forces us to rethink the importance of groundwater and seepage erosion on Mars because many Martian canyons thought to be formed from seepage have the same morphologic traits as Box Canyon. It also has caused us to redirect our research to the mechanics of waterfall erosion in bedrock and to transport of coarse sediment in shallow flows. The paper received significant media attention. This work was complemented by supporting studies analyzing sediment transport physics (Lamb et al, JGR, 2008), Cosmogenic dating in Box Canyon (Aciego et al, 2007), and seepage erosion in Hawaii (Lamb et al, 2007). Our future efforts are too look in more detail at the physics of canyon erosion by large floods (Lamb et al, in prep).

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