How do ocean ridges and deep-sea trenches support the theory of seafloor spreading?
1 Answer
Deep sea trenches are places where the speeding sea floor runs out of room and ocean ridges where new crust is being formed.
Explanation:
the theory of sea floor speeding is a part of the theory of plate tectonics. The theory proposes that there are plates of the earth crust that "float" on the mantle being moved by convection currents
The spreading of this plates can be observed and measured in the great rift valley of Africa. New crust can be observed being formed on the sea floor ridges. This new crust is pushed outward in two directions by the eruption of new crust coming up through cracks in the sea floor ridges.
In Iceland the eruption of new crust along the ridge can be seen in the formation of new islands and the existing islands of Iceland. These observations support the idea that the plates are spreading apart along the ocean ridges. Matching magnetic lines of reversal along both sides of the ocean ridge also lends support to the theory of sea floor spreading.
The subduction zones which form the deep sea trenches also support the theory of sea floor spreading. The trenches answer the question of if the sea floor is spreading where does the extra crust go? The earth is not getting bigger. The extra crust created along the ocean ridges is destroyed as the ocean plate is pushed under another ocean plate or continental plate.
The theory of sea floor spreading is now generally accepted as a fact. The mechanism of convection currents is still being questioned. That the sea floor is spreading is strongly supported by experimental observations.
The subduction zone destruction of ocean sediments brings up the question as to how the deep ocean sedimentary rock formations have been formed on the continental plates. This was a reason Simpson and other evolutionist at first opposed the continental drift theory that became the plate tectonics theory.
