It is hard to see in your pictures but it looks like either un-rendered surface faces or the lighting bug. In both cases this is just the state of minecraft at this current time. The issues have been lingering and annoying.
If the surface blocks are not rendering but you can see below them and the render when you step on them, you can mitigate this by turning OFF advanced OpenGL. This will not remove the issue but it did help me significantly with my game and a few other people.
If it is that the blocks are just not lit then walk into them, update the chunk some how (place a torch) and it will update the lighting calculations. This is an acknowledged Mojang issue that they are looking at solving with out killing world generation performance.
Another thing to consider are the mods you are running.. Wallhack probably alters the rendering a bit ;)