Is there a way to do proportional editing only on specific vertices? I have split several chains of vertices into groups in an attempt to access only one chain at a time for modeling, and it seemed to work yesterday. Today I can't isolate them when I use proportional editing. Is there something I need to do differently?
Here is the situation: I am building a model of the mountain below (it's on the Moon, so there aren't any files out there with its topographic information, and only one high-resolution photo exists). I have to figure out the relative height of its ridges by judging what the lighting means. So I drag parts of the vertex chains marking the ridges up and down using proportional editing, in right ortho view. The other vertex chains I don't want to move remain visible, otherwise I can't judge their relative position, but I don't want to move them.

Edit - I see now why it sometimes works - the circle marking the edge of the proportional effect is actually a sphere. If it doesn't touch adjacent vertex chains, then it works the way I want.
You can change the proportional editing type to 'Connected' to only affect the vertices connected to the ones you are moving:



This can also be enabled with Alt+O.