The motion of the block would create lorentz contractions which would decrease the length towards the direction of motion and thus decrease the over all volume of the moving block. There would be increase in mass due to the motion of the object near the speed of light. and thus creating an increase in density .

There is no relative motion between myself and the mountain thus the perception of the mountain will be that of rest space. On the other hand, from George’s perspective, as he is in relative motion with regards to the mountain, he will be observing Lorentz contraction of the same mountain. This will mean that the angles between the horizontal and the sides of the isosceles increases.