whether it carries oceanic or continental crust: Continental lithosphere is, on average, 150 km thick, although it can be thicker beneath mountain ranges. how far from a mid-oceanic ridge it is. Old oceanic lithosphere is up to 100 km thick, while at the axis of a mid-oceanic ridge, it may be only ten km thick.
Angola's borders are fairly straight compared to borders of any other country. The coastline and the southern lines are straight while the eastern and northern borders have stair-like shape but are fairly straight too. The country looks like a gun in some way too!