"I have two sand samples for comparison purposes. The reason I find these interesting is how the broken shell crumbs are mixed with the sand, but only at ridges where the waves lap the shore. . . The tide recedes and another ridge is formed with broken shells, and so on. The two samples include sand from the ridge (with broken shells) and from the beach right next to the first sampling point, the same sand, but without so many broken shells. One can learn a lot from studying the beach at low tide to see how wave action works. At high tide, the results aren't as noticable. I have watched the wave action near the shore to try to figure out why the ridge phenomenon occurs. . . . It has to do with the wave action in both directions. The wave comes in and pushes the broken shells up the incline of the beach, and then falls when the wave falls back (or is it the rip tide[?]) the broken shell fragments precipitate and collect along a line that eventually forms a ridge. The sand is more compact and durable than the broken shells, and so does not react to the wave motion so much. It's not the incoming action of the wave that forms the ridge, but rather the reverse action of the wave." Gary Foster |
