Geologic Landforms and Chronostratigraphic History of Charon as Revealed by a Hemispheric Geologic Map.

Geologic mapping has been used for over 200 years as a technique to synthesize a complicated surface into a more simplified product, identifying similar types of surface features, and placing them into a relative stratigraphy. Geomorphologic mapping has applied those principles to other terrestrial bodies throughout the solar system and has formed an important product set to understand these surfaces, plan future exploration, and conduct different scientific endeavors. We created a geomorphologic map of the New Horizons encounter hemisphere of Pluto's binary companion, Charon. Ten primary geomorphologic unit categories were identified, covering approximately 35% of Charon's surface, and we used lower resolution data to speculate about other regions of Charon. Over 1,000 linear features were mapped, nearly 90% of them are tectonic in nature, and we use these to provide evidence of Charon being active in its past. Additionally, we placed the mapped features into a chronostratigraphic sequence, and we present a possible surface history for the body. The northern terrain typified by large crustal blocks is the oldest, having fractured early in Charon's history, and potentially similar blocks were submerged in a cryoflow of which the now solid surface of Vulcan Planitia is the remnant today. Plain Language Summary: Planetary scientists will create geologic maps of a surface to perform different kinds of studies. Geologic maps identify features of different types and help to distill many different kinds of data into an easier to use format from which scientific investigations can be done. We have created such a map for Pluto's largest companion, Charon, imaged during the flyby of New Horizons in July 2015. This geologic map covers approximately 35% of the best‐imaged region of Charon, and we mapped 16 different geologic units, over 1,000 linear features, and a variety of albedo features. We developed a chronology that places these features in time‐order, and we provide potential interpretations of the different features that we mapped. We found that Charon has potentially one of the most convincing examples of possible large cryoflow(s) of any heretofore imaged body in the solar system. Key Points: We present a new geomorphologic map of New Horizons' encounter hemisphere of Charon, showing units, linear features, and albedo featuresWe introduce a chronostratigraphic system to place features and units in a historic sequence and contextWe interpret units and features in local, regional, and global context, pulling from knowledge of other solar system bodies [ABSTRACT FROM AUTHOR]