Goonies+Chester Copperpot+geologic wonders
Wednesday, September 6th, 2006
This what captian cummings had to say of my geology paper re: sea stacks.in bold atalics. and the paper below.
The rocks match the medallion I swear it. Chester Copperpot guys Chester Copperpot.
These features are pretty striking. They add a huge beauty to the coast.
Course Grade: P
On July 15th I participated in the coast field study of geology along the Northern Oregon coast. On this trip we looked in depth at several major geologic phenomena and their role in shaping the coast as we experience it today. I will explore my perceptions of the geologic phenomena that are known as sea stacks. These giant outcroppings of rocks were found at our stop at Arcadia Beach. The sea stacks that I will be referencing are located off of Highway 101 which is approximately 3 miles south of the town of Cannon Beach in Oregon.
Data and Observations
Ever since seeing the movie The Goonies in the theater in Vails Gate NY, I have been awed by the image of a sea stack. In this movie as a backdrop and as a key to finding the hidden pirate ship, the sea stacks at Cannon Beach play an integral role. It was only when I moved to Oregon six years ago did I know that they were located here in the Northwest. Always interesting to travel and see where we movies have been shot. Sometimes it is upsetting because the movie is trying to convince me that I am somewhere that the geology in the background indicates is impossible.
At Arcadia Beach, these massive outcroppings are at high tide surrounded by the ocean and to me look to be at least 80 feet tall and shaped more or less like a slanted pile of rubble (here a photograph would help illustrate the pattern). The sea stack appeared to be 10-20 feet from the nearest cliff walls that ring the beach. At low tide it is possible to observe various forms of marine life clinging to the bottom of the stack in its crevasses and pock holes. At the Arcadia sea stack I observed bluish-green sea anemones and tight clusters of mussels. The rock itself was angular and blocky with a reddish-brown hue.
These stacks can be seen all along the Oregon coast. I found them to be always out in the sea a bit but sometimes surrounded by the ocean and on Arcadia Beach both in the sea and on the beach. They are common along the Oregon coast, but they do vary as to their composition and their geologic history. They do make the coast what it is.
Discussion
Based on my observations I initially thought that the sea stacks at the site were sedimentary in origin. This is because of their proximity to the coast and all of the sand associated with the site. It was not until the discussions with the group continued did I realize that the stacks were a mix of sedimentary and volcanic rock. It was explained that these particular sea stacks were remnants from a time long ago when Columbia River Basalt flowed from Eastern Oregon along lowlands and ancient streambeds to the Pacific Ocean. It is here at the ocean where the basaltic lava had explosive contact with the water and sediment in an estuary. The basalt being of a higher density then the water-saturated sediment that it came in contact with was forced below the sand. However this process was not all uniform. In the process of this initial contact mixing of the sediment and the lava took place producing a conglomeration of materials cemented together. Evidence of this can be seen in the sea stack itself.
Another product of this explosive mixing can be seen in the formation of pepperite. According to what I gleaned from the group discussion, this rock that made the stack on Arcadia Beach is a mixture of the in situ sediments that make up the beach and the invasive Columbia River Basalt.
What are shown presently at this site are the stacks in their eroded state. It has taken millions of years for these stacks to form their present shapes and sizes. It is possible that they were once connected to the headlands that ring the present day beach. Sea stacks are the present day evidence of massive basalt flows and the erosive power of the ocean.
Anyway that was what it was. I’d love to talk to yall 1on1 about it anytime and I do do geology tours for your group or school.