How do I allow touch on sprites only where not overlapped

Hi. How might I allow touch on sprites only on the area not overlapped by another sprite? Currently when I touch it calls the actions from both objects.

Eg Rotating 'sky' sprite which falls behind the 'ground' sprite. Currently when I touch the ground it is also calling action for the sky which is below.

Thanks

Have you a CAPX I can look at ?

Sure... what is the best way to get this to you

The most common way here is to use dropbox and add a link.