patching dems

[Dan Riker]

Hello, I hope all is well. 
I would like to thank all those who responded to my first questions about extracting dems.  My problem now is that 3 of my dems are of one color scheme and the other four of another scheme after they are either patched or added with r.mapcalc.  A 3d representation shows the three are taller than the other 4, and the line connecting them is nearly vertical.
Any suggestions?
Dan Riker