Experiments using the Sandbox Model to Study Internal and External Deformation
For my research, I studied the internal and external deformation of
6 layers of sand inside a sandbox model. The dimensions were 9.5
cm in length, 14 cm in width, and 1.2 cm in depth. The design was
modified from Persson and Sokoutis (2002). We did six separate runs:
two with no erosion, two with erosion on the pro-wedge, and two with erosion
on the retro-wedge. For every 8 mm of horizontal shortening, we eroded
2 mm of sand from either the pro-wedge or retro-wedge. We used two
methods of erosion: a vacuum and a razor. Both methods were used
in each of the four runs involving erosion, only on separate sides of the
model. When the pro-wedge was eroded there was a significant difference
in the internal deformation of the sides of the model that were eroded
using a vacuum and eroded using a razor. On the side eroded with
the razor, material was moved as far away from the wedge as possible, but
remained in the system. The result was that the layers in the side
eroded with the razor were thickened, but no distinctive folds or shear
planes developed. In the side eroded with the vacuum, the folds and
shear planes were clearly defined. Another result from the experiment
showed slightly steeper axial and shear planes in the wedges that were
not eroded than in the eroded retro-wedges. The difference was ~10-20*.