Raymond Effect
Raymond Effect is a flow effect in ice sheets, occurring at flow divides, which gives rise to disturbances in the stratigraphy, showing unusual arches or anticlines [1] called Raymond Arches. The stratigraphy is detected by radio-echo sounding. The Raymond effect arises from the unusual flow properties of ice. It is of importance because it provides field evidence for the flow properties of ice. In addition, it permits dating of changes in ice flow and the establishment of changes in ice thickness.[2] The effect was first predicted by Charles F. Raymond.[3]
Ice viscosity is stress-dependent, and in zones where the (deviatoric) stresses are low, the viscosity becomes very high. Near the base of ice-sheets, stress is proportional to the surface slope, at least when averaged over a suitable horizontal distance. At the flow divide, the surface slope is zero, implying that near the base of the ice-sheet, the viscosity increases. This diverts ice flow laterally, and is the cause of the characteristic anticlines, which are in effect draped over the high viscosity area.
References
- ^ Vaughan, David G.; Hugh F. J. Corr; Christopher S. M. Doake; Ed. D. Waddington (25 March 1999). "Distortion of isochronous layers in ice revealed by ground-penetrating radar". Nature. 398 (6725): 323–326. doi:10.1038/18653.
- ^ Conway, H.; B. Hall; G. Denton; A. Gades; E.D. Waddington (1999). "Past and future grounding-line retreat of the West Antarctic Ice". Science. 286: 280–283. doi:10.1126/science.286.5438.280.
- ^ Raymond C.R. (1983). "Deformation in the vicinity of ice divides". Journal of Glaciology. 29 (103): 357–373.