What shapes a terrestrial planetary surface

impact cratering: excavation of surface by asteroids or comets striking the planet (early on in planet life, affects all planets equally)

• hits planet at 10-70 km/s
• solid rock is vapourized, a crater is excavated + matter ejected in all directions

volcanism: eruption of lava from interior (size determines how long, requires internal heat)

• Viscoity of lava (typically basalt) determines the type of volcano
• low viscosity produces flat lava planes, on the moon
• medium viscoity produces shallow-sloped sheild volcanos, such as Olympus Mons
• high viscosity produce steeply sloped stratovolcanos, such as mount hood

tectonics: disruption of lithosphere by internal stresses (size determines how long, requires internal heat)

• convection - compression in lithospere (tectonics) create mountains
• extension creats valleys

erosion: wearing down of geological structures by wind, water, ice action. (ultimately dominant, but requires outgassing first to make atmosphere)

• valleys shaped by glaciers
• canyons carved by rivers
• sand blown by wind
• ALSO BUILDS:
• sand dunes
• river deltas
• sedimentary rock