Again, the layers above the Great Uncomformity (blue line) are horizontal. The layers below the Great Unconformity are laid in at an angle. The angled layers all get cut off flat at the Great Unconformity. There is no reasonable explanation for this other than that the lower layers got tilted, and then erosion wore things down to the Great Unconformity before sedimentation built new layers back up. This must have taken millions of years.
Regarding the angle, yes, the illustration has the angle steeper than the layers are in reality. That is because the vertical scale of the illustration is exaggerated in comparison to the horizontal scale. That's an artist technique to help us see all the vertical layers.
Regarding the two blocks, I don't know if that can be seen with the naked eye. There are many ways to detect the rocks down there, including wells or instrument readings from the surface.