Abstract
Although amphitheatre-shaped valley heads can be cut by groundwater flows emerging from springs, recent geological evidence suggests that other processes may also produce similar features, thus confounding the interpretations of such valley heads on Earth and Mars. To better understand the origin of this topographic form, we combine field observations, laboratory experiments, analysis of a high-resolution topographic map and mathematical theory to quantitatively characterize a class of physical phenomena that produce amphitheatre-shaped heads. The resulting geometric growth equation accurately predicts the shape of decimetre-wide channels in laboratory experiments, 100 m-wide valleys in Florida and Idaho, and kilometre-wide valleys on Mars. We find that, whenever the processes shaping a landscape favour the growth of sharply protruding features, channels develop amphitheatre-shaped heads with an aspect ratio of .
| Original language | English (US) |
|---|---|
| Pages (from-to) | 245-254 |
| Number of pages | 10 |
| Journal | Journal of fluid Mechanics |
| Volume | 673 |
| DOIs | |
| State | Published - Apr 25 2011 |
Funding
We would like to thank The Nature Conservancy for access to the Apalachicola Bluffs and Ravines Preserve, and K. Flournoy, B. Kreiter, S. Herrington and D. Printiss for guidance on the Preserve. We thank B. Smith for her experimental work. It is also our pleasure to thank M. Berhanu. This work was supported by Department of Energy Grant FG02-99ER15004. O.D. was additionally supported by the French Academy of Sciences.
Keywords
- fingering instability
- geophysical and geological flows
- pattern formation
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Applied Mathematics