  Recent data from heavy ion collisions at RHIC show unexpectedly large
near-angle correlations that broaden longitudinally with centrality. The
amplitude of this ridge-like correlation rises rapidly with centrality, reaches
a maximum, and then falls in the most central collisions. In this talk we
explain how this behavior can be easily understood in a picture where final
momentum-space correlations are driven by initial coordinate space density
fluctuations. We propose $v_n^2/\epsilon_{n,part}^{2}$ as a useful way to study
these effects and explain what it tells us about the collision dynamics.
