  The North Celestial Pole Loop (NCPL) provides a unique laboratory for
studying the early stage precursors of star formation. Uncovering its origin is
key to understanding the dynamical mechanisms that control the evolution of its
contents. In this study, we explore the 3D geometry and the dynamics of the
NCPL using high-resolution dust extinction data and H I data, respectively. We
find that material toward Polaris and Ursa Major is distributed along a plane
similarly oriented to the Radcliffe wave. The Spider projected in between
appears disconnected in 3D, a discontinuity in the loop shape. We find that the
elongated cavity that forms the inner part of the NCPL is a protrusion of the
Local Bubble (LB) likely filled with warm (possibly hot) gas that passes
through and goes beyond the location of the dense clouds. An idealized model of
the cavity as a prolate spheroid oriented toward the observer, reminiscent of
the cylindrical model proposed by Meyerdierks et al. (1991), encompasses the
protrusion and fits into arcs of warm H I gas expanding laterally to it. As
first argued by Meyerdierks et al. (1991), the non-spherical geometry of the
cavity and the lack of OB stars interior to it disfavor an origin caused by a
single point-like source of energy or multiple supernovae. Rather, the
formation of the protrusion could be related to the propagation of warm gas
from the LB into a pre-existing non-uniform medium in the lower halo, the
topology of which was likely shaped by past star formation activity along the
Local Arm.
