Short answers, pulled from the story.
Geomorphology is the scientific study of the origin and evolution of topographic and bathymetric features generated by physical, chemical, or biological processes operating at or near Earth's surface. Geomorphologists seek to understand why landscapes look the way they do, study landform history and dynamics, and predict future changes using field observations, physical experiments, and numerical modeling.
The study of landforms dates back to Classical Greece. In the 5th century BC, the historian Herodotus observed that the Nile delta was actively growing into the Mediterranean Sea. The medieval Persian scholar Abu Rayhan al-Biruni (973-1048) hypothesized that the Indian Ocean once covered all of India, and the Song dynasty scientist Shen Kuo (1031-1095) used fossil shells and eroded mountains to theorize landscape change driven by erosion and silt deposition.
William Morris Davis developed the geographical cycle, or cycle of erosion, between 1884 and 1899. The model described how a river carves progressively deeper valleys through flat terrain until side valleys erode and flatten the land at a lower elevation, with tectonic uplift then restarting the cycle. The model has been largely superseded due to its lack of predictive power and qualitative nature, though it remains a common tool in historical geology for establishing denudation chronologies.
The term geomorphology appears to have first been used by Laumann in an 1858 work written in German. It came into general use in English, German, and French after John Wesley Powell and W. J. McGee used it during the International Geological Conference of 1891.
Primary surface processes include wind, waves, chemical dissolution, mass wasting, groundwater movement, surface water flow, glacial action, tectonism, and volcanism. More specialized processes include periglacial freeze-thaw action, salt-mediated change, and marine current activity on the seafloor. Tectonic effects range from earthquake-driven land submergence occurring in minutes to the formation of orogenic mountain belts over tens of millions of years.
Planetary geomorphology studies landforms on Mars and other terrestrial planets, identifying signs of wind, fluvial, glacial, mass wasting, meteor impact, tectonic, and volcanic processes. Because Mars lacks biology, its landscapes allow geomorphologists to study surface processes in isolation from biological influence. Geomorphologists often use Earth analogues to interpret the surfaces of other planets.