  Systematic geomorphological mapping and detailed landform analysis using the
highest resolution images obtained by the New Horizons spacecraft reveal the
presence of a range of differentiable terrains on Charon, the largest moon of
Pluto, that were not examined in detail by the early studies. The most
important findings of our work include (1) truncation and omission of large
craters (diameters > 30-40 km) and their crater rim ridges along the eastern
edges of several north-trending, eastward-convex, arcuate ranges in Oz Terra,
(2) lobate ridges, lobate knob trains, and lobate aprons resembling glacial
moraine landforms on Earth, (3) dendritic channel systems containing hanging
valleys, and (4) locally striated surfaces defined by parallel ridges, knob
trains, and grooves that are > 40-50 km in length. The above observations and
the topographic dichotomy of Charon' s encountered hemisphere can be explained
by a landscape-evolution model that involves (i) a giant impact that created
the Vulcan Planitia basin and the extensional fault zone along its northern
rim, (ii) a transient atmosphere capable of driving N2-ice glacial erosion of
the water-ice bedrock and transporting water-ice debris to sedimentary basins,
(iii) regional glacial erosion and transport of earlier emplaced impact ejecta
deposits from the highlands of Oz Terra into the lowland basin of Vulcan
Planitia, (iv) syn-glaciation north-trending thrusting interpreted to have been
induced by Charon' s despinning, and (v) the development of a water-ice debris
cover layer over subsurface N2 ice below Vulcan Planitia during global
deglaciation. The infilling of the Vulcan Planitia could have been accompanied
by cryovolcanism. The extensive modification of impact craters means that the
crater size-frequency distributions from Charon should serve only as a lower
bound when used to test the formation mechanism of Kuiper belt objects.
