There are dozens of craters on the left side of the dotted line but not much ejecta. Older terrain where impacts don’t throw material but turn into gas which snows back down to the surface. Leaving holes that looks like it was melted into a crater shape.
On the right side of the line are very few impacts. This tells me the the rough mountains here are not as old, formed from an impact? in the sea that caused a wave of ice to be deposited on higher terrain.
Impacts at the top right of the picture “melted it’s surroundings” and refilled the crater and caused discoloration as it flowed into the sea, a different substance then the left side of the redline, that did not vaporize that became liquefied for a time.

An Eskimo village at the top left of Alaska is built upon a gravel bar pushed there by pack ice. By tradition, Eskimos fish to survive… But they know to head for higher ground if the wind starts blowing to the east because the ice from the Bering Sea will flow towards them and it doesn’t stop when it hits land. People are killed every year from ice that land, breaks and flips over crushing them as the ice flow piles up sometimes stories high against the shoreline. (they also have a large well-built fence around the village to keep out the polar bears… a bear that does not hibernate)

F: Heh. I see no need to shout. Simply using the word “planet” in describing Pluto makes the point quite well.

” . . . Though we only have a limited archive of high resolution pictures of Pluto that were taken when New Horizons did its close fly-by of the PLANET!!!!!! in July 2015 . . .”