  Using $\lambda$-21-cm galactic neutral atomic hydrogen data from the HI4PI
survey of Bekhti et al. (2016) and 0.75-30 MeV $\gamma$-ray emission from the
Imaging Compton Telescope, we have searched for the origin event that
accelerated high velocity cloud Complex M. Radio plots of $l-b$, $l-v$, and
$b-v$ show a cavity centered at ($l$, $b$) $\sim$ (150$^{\circ}$,
50.$^{\circ}$) and extending about $\pm$33$^{\circ}$. The best view of the
cavity is at a velocity of -25 km s$^{-1}$, which shows a circular cross
section on the back (receding) face. Complex M, at -85 km s$^{-1}$, is on the
front (approaching) face. The $\gamma$-ray emission reveals several minima, the
largest centered at ($l$, $b$) $\sim$ (150$^{\circ}$, 50.$^{\circ}$) and
coincident with the position and extent of the cavity seen in the radio data.
Using the know distance to Complex M and assuming that the cavity is spherical,
we can bootstrap the distance to the original, explosive source of the cavity,
D = 307 pc, calculate the radius of the cavity, R = 166 pc, and approximate the
expansion velocity, V$_E$ $\approx$ 40 km $s^{-1}$, of the cavity. The total
energy of the expanding cavity is 3.0 $\pm$ 1.0 ${\times}$ 10$^{50}$ ergs, well
within the range of a single supernova. These results indicate that this
explosion took place about four million years ago. As the blast wave from this
supernova propagated outwards, it began to sweep up interstellar gas and carved
out the Local Chimney, a low-density extension of the Local Bubble that reaches
into the galactic halo.
