Duddley...A Logarithmic scale shows DECADES equally spaced...100, 1000, 10,000 etc. Octaves would be 20, 40, 80, 160, etc.

A Log scale is used when the quantity being plotted behaves in a Logarithmic way. If you plot such a quantity on a linear scale and you pick the scale so that it is appropriate for one end of the range, the other end will be all scrunched up or stretched out, so that it cant't be read. (Take one of your Log scale plots and try to plot it on a linear scale).

If one axis is linear, and the other is logarithmic, the plot is called "Log/Linear".