Plate tectonics theory
The plate tectonics theory tries to explain the movement of the Earth's lithosphere. The Earth's surface is made up of a series of large plates that can travel up to 2 or 3 cm per year. Convection currents beneath the plates drive the plates in different directions; the source of the heat driving the convection currents is from the radio active decay taking place within the Earth's core. The idea behind the plate tectonics theory originates from meteroloigst Alfred Wegner's ideas of continental drift. He observed that the continets seemed to fit together like a jigsaw forming a super continent called Pangaea.
Overall There are seven major plates: North America, South America, Eurasia, Africa, Indo-Australian, Pacific and Antarctica. Mantle convection, Earth rotation and gravity are all drivers of the movement. As these plates interact they form plate bounnderies which causes many different features to emerge.
Overall There are seven major plates: North America, South America, Eurasia, Africa, Indo-Australian, Pacific and Antarctica. Mantle convection, Earth rotation and gravity are all drivers of the movement. As these plates interact they form plate bounnderies which causes many different features to emerge.
Evidence for plate tectonic theory
There are three main pieces of evidence that support plate tectonic theory the first is the age of the earth’s crust showing that new rock has been formed and it still likely to be forming. The second discovery was the magnetic variances in the basaltic rock found on the ocean floor along the Mid-Atlantic ridge, the phenomenon is now known as paleomagnetism. This showed that the Earth’s crust must be growing with time due to the north flitting from hemisphere to hemisphere periodically leaving a magnetic fingerprint in the newly formed magnetic elements in the earths crust. The third was sea floor spreading which now can be imaged and calculated using satellites. America is moving 2.5cm a year away from the UK. This supports plate tectonic theory as it shows that there has to be plates for continents to
move independently to each other.
Evidence against plate tectonic theory
The evidence against plate tectonic theory is due to the mechanics of plate movement. This is because convection cell currents have not been proved conclusively to exist due to technological limitations we have never been able to get deep enough into earth to prove the theory. The main fault in convention cell currents is the evidence collected which suggests that these cells are impossible to
occur, furthermore there is no evidence to suggest that they do occur it is all theory. Furthermore more questions arise when you ask how the plates formed and how enough energy is gained through convection to move truly gargantuan slabs of rock! The other niggle is that we have little to no conclusive evidence that subduction actually occurs and with the earth not expanding what happens? Finally convection cell currents do not have the force to form mountain ranges such as the Andes and Himalayas so how did they form?
occur, furthermore there is no evidence to suggest that they do occur it is all theory. Furthermore more questions arise when you ask how the plates formed and how enough energy is gained through convection to move truly gargantuan slabs of rock! The other niggle is that we have little to no conclusive evidence that subduction actually occurs and with the earth not expanding what happens? Finally convection cell currents do not have the force to form mountain ranges such as the Andes and Himalayas so how did they form?