Why does my terrain warp when I unwrap? I used many areas of Google terrain from Sketch Up and joined them together in Cycles.  then I stitched them together and removed doubles.  As you can see, when I unwrap it's warped.  I'm a newbee, be gentle :-)
Switch to top view, then in edit mode select all the mesh, hit U button to unwrap and from the menu select Project from View (Bounds)