Symbolising with two attributes

Discussion created by hkj on Oct 2, 2011
Latest reply on Oct 5, 2011 by spk578

I have a series of points (representing water level data from wells) that I want to symbolise in two ways: first I want the size of the symbol to be proportional to well depth, then I want the colour to vary according to water level response to the ChCh earthquake (spike, positive offset, negative offset, no change, etc).

I can't see a way of doing this. Can anyone help?

Many thanks