ABSTRACT
The average aspect ratios of these 60 pebbles are depicted in Figure 6 using three different shrinking ratios. It is really interesting that they all converge to constant final elliptical shapes in all three cases, neither keeping initial circles nor being flatter further. This results at least indicates that under some a natural environments, constant shape of pebbles could be reached just like what Wald (1990) pointed out. In this work, we note that the final aspect ratios are strongly dependent on the shrinking ratios. When shrinking the box with a ratio of 0.85, we get ρ= 0.87. Similarly, ρ= 0.91 at shrinking ratio of 0.9 and ρ= 0.97 at shrinking ratio of 0.95. That is the final aspect ratio is almost the same as the shrinking aspects. We know that the shrinking ratio in this work is related to the natural lateral frictions and impacting of pebbles, and erosion by sea salty water. The problem is that how to choose the shrinking ratio and how to correlate shrinking ratio with these natural process. This would be done next step. Beside this, we maybe have to pay attention onto the origins of pebbles, such as granites, or sandstones and or shales. Because of their different internal textile, some of them will be easily worn in some specific orientations.
