title: scatter plot data does not appear on continents in 'hammer' basemap
body: <p>I am attempting to plot a dataset over the 'hammer' basemap using a scatter plot. However, the data points won't plot on top of the continents. I noticed in the matplotlib <a href="http://matplotlib.org/basemap/users/examples.html" rel="noreferrer">example</a>, there is also not data on the continents (I assumed this was due to the nature of the example). I'm wondering if I'm doing something wrong, or if data cannot be plotted on top of the continents using 'hammer' by design. </p>
  
  <p>If this is the case, is there an ideal basemap to use to plot scatter plot data over the whole Earth (using a relief map would be great, but I would settle for anything at this point)?</p>