The Geology of Pluto

Pluto's complex surface geology records nearly its entire history, from the heavy bombardment era more than 4 b.y. ago to the present day. The highly partitioned nature of Pluto's geology can be attributed to combinations of exogenic and endogenic processes acting to varying degrees upon the landscape; the primary influence appears to be atmosphere-surface volatile transport, which is strongly controlled by Pluto's eccentric seasons and climate zones. The hemisphere seen at close range during the New Horizons flyby shows ongoing surface geological activity centered on a vast basin containing a thick deposit of predominantly nitrogen ice that is undergoing thermal convection. Surrounding terrains show active glacial flow of volatile ices and apparent transport and rotation of large, buoyant water ice crustal blocks. A sequence of methane ice deposits displaying a complex bladed texture stretches around much of Pluto's equatorial region. Tall, enigmatic mounds with large central depressions are conceivably cryovolcanic. The most ancient and cratered terrains, seen in the northern and western regions of the nearside hemisphere, are extensionally faulted, partly eroded by glaciation and sublimation, and mantled by volatile ices to varying degrees at high latitudes and by a dark blanket of atmospheric haze particles in equatorial regions.