How do you make this kind of terrain?

Geology and Terrain
#1

I’am trying to make this kind of terrain, for unreal engine:

I am already working the second week on this project, but the only good result that i can get is look like this:

And thats how it looks inside Unreal:

It is good but still far from that i want to achive. And if you look inside Google Earth and compare you will understand what i mean.
It seems that I have exhausted all my ideas and it’s time for me to turn to others.

How do you make this kind of terrain?

You can download the project here.
And the kmz-file for google earth here.

Thanks.

#2