Wednesday, August 5, 2009
A Unique Spectacle
Hello everyone, what a great day for another outdoor excercise. I have to admit that out of all the islands we've visited during this class, Spectacle Island is my favorite. This is probably due to the fact that not too long ago this same island was a dump. What an amazing turn around. Today we broke up into several groups and each group made observation of findings on the beach. My group (Sam, Nick, and I) started at the top of the beach. The debris on the top of the beach was mixed and in much larger sizes. We found big pieces of clear glass, green glass, blue glass, muscle shells, periwinkles and peices of plates. As we dug deeper we noted that the debris became finer and was less abundant and the sand was damp. This was a great example of the "Brazil Nut Phenomena". The sand was damp because when there is high tide the water covers all that area, but when the tide is low the area that was covered with water is now been hit by the sun. However, the sun can't reach the beach sand below that is covered by the larger peices of glass, rocks and plate debris at the top. As my group and I moved down to a lower area on the beach we found that there were still rocks covering damp sand. But the larger peices of glass and plates we found on the top of the beach were less in quantity. This happens because of the effects of tides and the long short transport. The rocks are much heavier to move from one area to another, but the peices of glass are much lighter. This enables the tides to push the peices of glass higher up on the beach.