Continental Drift, Seafloor Spreading, and plate tectonics
What theories about Earth do you believe?
The Continental Drift- theory that the continents where once one huge landmass.
Seafloor Spreading- theory that the ocean seafloor spreads the magma surfacing in the mid ocean ridge
Plate Tectonics- theory that different landmasses are made by movements of tectonic plates
1. Continental Drift
The theory that the continents were once together as one whole land mass, but then were separated by huge force called plate tectonics. This force did not separate the plate quick and easy, but it moved the land slowly over many years. Personally i believe in the continental drift. Alfred Wegener was the first to discover this theory. He was looking at a map, and he observed that the continents, specifically Africa and South America, "fit together like a puzzle piece." After Alfred passed away more evidence was found, things like tropical plant fossils found in Antarctica, the same freshwater animal fossils found continents away, and glacier deposits in warm areas! These pieces of evidence in addition to the research our class has done in honor of Alfred Wegener must mean something. The continental drift is the best solution.
Earth 100 Million Years From Now
2. Seafloor Spreading
The theory that the seafloor spreads by the oceanic plates moving away from each other as the magma from the mantle pushes up through the crack to create new rocks as it collides with the water. As the Seafloor pushes out it is pushes underneath the continental crust. This is called a subduction zone. After awhile of being pushed underneath the continental crust it returns to the magma melts down and repeats this cycle. I believe that seafloor spreading is true because we have found mid ocean ridges where magma rises and makes new rocks, where by the continental crust we have found older rocks that are about to be refreshed through the melt down process. We have also discovered magnetic pole reversals. Through all of this evidence and the plates move at an average of two inches a year. The oceanic plates are mostly divergent, which means that they move apart only to leave the middle to be filled by magma. In class we produced an experiment that was originally explaining plate tectonics, but when we used gram-crackers and frosting, we observed what would happen when the oceanic plates move apart and the frosting, or magma, moves in between the two plates.
Animations of seafloor spreading:
Sea Floor Spreading with Bill Nye
The theory that the earth is split up into several different plates that move at an average pace of two inches a year. There are several different movements convergent, divergent, and transform. In convergent, two plates move together. On divergent, two plate move away from each other. Then transform, the plates slide past each other. It is said in theory that the movements of these plates is how different land forms are made. Personally i believe plate tectonics. The seafloor spreading, technically isn't spreading, and the continental drift is caused by the moving of the plates. The plates move because of convection currents, which are the cycle of warm and less warm magma cycling underneath the plates which heats them up and causes them to move. We learned in class about convection currents and how they move through the beaker on the hot plate and the candle in the coffee container.
BN Pangaea and Plate Tectonics I