  We report new observations of multiple transitions of the CS molecular lines
in the SgrA region of the Galactic center, at an angular resolution of 40"
(=1.5 pc). The objective of this paper is to study the polar arc, which is a
molecular ridge near the SgrA region, with apparent non-coplanar motions, and a
velocity gradient perpendicular to the Galactic plane. With our high resolution
dense-gas maps, we search for the base and the origin of the polar arc, which
is expected to be embedded in the Galactic disk. We find that the polar arc is
connected to a continuous structure from one of the disk ring/arm in both the
spatial and velocity domains. This structure near SgrA* has high
CS(J=4-3)/CS(J=2-1) ratios >1. That this structure has eluded detection in
previous observations, is likely due to the combination of high excitation and
low surface brightness temperature. We call this new structure the connecting
ridge. We discuss the possible mechanism to form this structure and to lift the
gas above the Galactic plane.
