Fault block mountains form when large blocks of crust are uplifted and tilted along normal faults. The uplifted blocks are called block mountains. They are formed by the movement of large crustal blocks<span> when forces in the Earth's crust pull it apart. Some parts of the Earth are pushed upward and others collapse down.</span>
Answer:
At an angle of 
Explanation:
Assume the river flows from East to West so for the swimmer to cross across it, assume he crosses it from West to East.
The resultant speed will be given by

If you are asking for a proof on having at least 3 dimensions in space, you can find the physical proof anywhere in your daily life activities. Just the fact that solids have volumes is a proof already that we live in a three-dimensional space. We can move forwards, backwards, sidewards and in all other directions possible.
When you go right into detail, the fundamental laws governing these proofs are very technical. They have differential equations to show as proof. It is too detailed to discuss here. The important things is that, these fundamental laws are what explains the science in our basic activities and natural phenomena:
*Gravitation and planetary motion
* Translation, rotation, magnetic field, forces
* Integrals of equations:
I believe the answer to your question is “Lithosphere plate boundaries”
The planet Earth is covered by a layer formed by land and rocks called the earth's crust or lithosphere. This crust is not smooth and uniform, but rather irregular and composed of tectonic plates, also called lithosphere plates. These plates are not fixed as they are under the magma (high temperature molten rock).
Hope this helps!:)