The Principle of Horizontally tells us that layers of sediments deposited on the Earth's surface are originally deposited horizontally. If these sediments are undisturbed, then they will remain that way. That is why some areas like Indiana, USA are "flat as a pancake". The lithified sediments that have become rock are flat. When those sediments are disturbed (e.g. through actions of water, glaciers, volcanic events, earthquakes, folding, faulting, orogenic events etc) that can create elevation changes and creates landforms. Landforms are also created based on the lithology (rock type) as some rocks weather faster than others leading to positive and negative relief areas.
The reason I kept asking
@quentin1974 about plate tectonics applies here. Since he never could provide evidence, I'd like to say what I've been wanting to say.
The theory of Plate Tectonics essentially states that our continents can move. Our continental crust varies a lot, but the average composition is considered a granodiorite. These rocks are less dense and essentially float over the Asthenosphere (a layer of the mantle).
The mantle has a lot of heterogeneity. One would think it is not possible to study the mantle because of it being too far down in the Earth. However it has been possible through various geophysical and geochemical techniques.
Geophysics - Major techniques of geophysics include 3D seismic tomography which is generated through S and P waves. These seismic waves are created from seismic activity like earthquakes. When an earthquake happens, it releases off S and P waves which (to make a long story short) are affected in their speed and direction when they go through different medium and densities (solid, semi-solid, liquid etc).
An example of what this data might look like is seen below. This figure (Kennett, B. L. N., Tkalčić, H, 2008) depicts the percent perturbation, meaning the amount of variation found in S wave speed. This is important because this means the physical and chemical properties of the medium have changed, which allow boundaries to be set in place i.e. core-mantle boundary.
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Geochemical - Geochemical data is much more limited because it is dependent on finding physical samples of igneous rock at the surface which have erupted or otherwise ended up at the surface of the Earth. Because these rocks are solidified and found at the surface, they are best used to understand previous compositions and mantellic evolution.
Geochemical and Geophysical studies have brought a wealth of information to mantellic evolution. By using 3D seismic tomography, geologists have found distinct zones in the mantle being able to better understand mantle circulation (both upwelling and subduction), along with mantle composition. Mantle chemistry can rarely be tested at the surface of the Earth, but through seismic waves, their responses to different changes in composition (i.e. speed change, direction change) are indicative of differences in the media.
These upwelling and downwelling cycles play important roles in the movement of our continents. These cycles, which are well documented, depend on a spherical Earth. Where is the core on a flat planet? What happens to the mantle? We know a mantle exists, look what is happening in Hawaii, that's hotspot volcanism! That lava is coming from somewhere...
I've googled it, and I can't find an answer as to how FEers explain how plate tectonics can happen on a flat Earth. The continents are most certainly moving. This has been verified by satellites, fossil evidence, the fact that earthquakes exist, and the fact that India smashed into Asia to create the Himalayas. If continents don't move, where the hell do mountains come from? Where do earthquakes come from? They can't move on a flat Earth. They move because we live on a round Earth.
Source:
Kennett, B. L. N., Tkalčić, H, 2008, Dynamic Earth: crustal and mantle heterogeneity, Australian Journal of Earth Sciences, v. 55, p. 265-279.
Now lets stop this nonsensical discussion...
/thread.
