title: Plot time series and image in R so that x axis labels line up perfectly
body: <p>I am trying to plot a time series (a seismograph) with a corresponding spectrogram in R.
  Since I would like to compare the time series with the spectrogram, the X axis labels on the time series need to line up with the X axis labels on the spectrogram.  However, I'm having a lot of trouble with this.  The best I've been able to do so far is use</p>
  
  <pre><code>par(mar=c(0,10,0,8))
  </code></pre>
  
  <p>and try to manually force the spectrogram labels to line up with the time series labels by tweaking the spectrogram margin.  Of course this is only approximate and they still do not line up perfectly.  Is there a way to make the axes generated by the code below match up with each other?</p>
  
  <pre><code>par(mfcol=c(2,1))
  plot(seq_len(1000)*0.01, sin(2*pi*seq_len(1000)*0.01), type="l",xlab="Time",
  ylab="Amplitude", main="Time Series", xlim=c(1,10))
  image(seq_len(1000)*0.01,seq_len(100)*0.1,array(runif(1000000),dim=c(1000,100)),
  xlab="Time", ylab="Frequency", main="Spectrogram", xlim=c(1,10))
  </code></pre>
  
  <p>Thanks in advance!</p>