  The Wisconsin H-Alpha Mapper (WHAM) Northern Sky Survey has revealed a loop
of H II reaching 1300 pc from the Galactic midplane above the Cas OB6
association in the Perseus sprial arm. This enormous feature surrounds and
extends far above the "W4 Chimney" identified by Normandeau et al. and appears
to be associated with the star formation activity near the W3/W4/W5 H II region
complex. The existence of this ionized structure suggests that past episodes of
massive star formation have cleared the H I from an enormous volume above the
Perseus arm, allowing Lyman continuum photons from O stars near the Galactic
midplane to reach into the halo.
