\begin{pspicture}(-0.4,-2)(10,1)
\psset{xunit=0.1cm}
\psaxes[Dx=10]{}(0,-1)(100,-1)
\psset{linewidth=15pt}
\psline[linecolor=darkgray](0,1)(40,1)
\psline[linecolor=lightgray](40,1)(60,1)
\psline[linecolor=darkgray](60,1)(100,1)

\psline[linecolor=darkgray](0,0)(40,0)
\psline[linecolor=darkgray](60,0)(100,0)
\psline[linecolor=black,linewidth=2pt,linestyle=dashed](40,0)(60,0)
\rput(-4,1){$S_1$}
\rput(-4,0){$S_2$}
\rput(50,-2){Position (kb)}
\end{pspicture}



