Is it normal for all the x-values on a physics log-log graph to be negative?

[ChuChuChiggaChigga]

I have to draw a graph of log(period) vs log(distance), with distance being the independent variable. I 'logged' both sets of data on my calculator and all the x-values were negative. Is this normal? Also, how would I plot that? On the left side of the y-axis?