  Photodissociation regions (PDRs), where the (far-)ultraviolet light from hot
young stars interact with the gas in surrounding molecular clouds, provide
laboratories for understanding the nature and role of feedback by star
formation on the interstellar medium. While the general nature of PDRs is well
understood - at least under simplified conditions - the detailed dynamics and
chemistry of these regions, including gas clumping, evolution over time etc.
can be very complex. We present interferometric observations of the 21 cm
atomic hydrogen line, combined with [CII] 158 $\mu$m observations, towards the
nearby reflection nebula IC 63. We find a clumpy HI structure in the PDR, and a
ring morphology for the HI emission at the tip of IC 63. We further unveil
kinematic substructure, of the order of 1~km~s$^{-1}$, in the PDR layers and
several legs that will disperse IC 63 in $<$0.5 Myr. We find that the dynamics
in the PDR explain the observed clumpy HI distribution and lack of a
well-defined HI/H$_{2}$ transition front. However, it is currently not possible
to conclude whether HI self-absorption (HISA) and non-equilibrium chemistry
also contribute to this clumpy morphology and missing HI/H$_{2}$ transition
front.
