Sedimentology, or the study of sedimentary rocks and the processes that produce them, encompasses and is connected to a wide range of phenomena. Weathering, erosion, transportation, deposition, and diagenesis are the five fundamental processes defined by the word sedimentation. Sedimentology and geomorphology are both concerned with the study of the earth's surface features. The study of rivers is also shared by sedimentology and hydrology. —channels. River channels are constructed in part or entirely as a result of flowing water and sediment transfer, often known as river work. Sedimentary rocks cover up to 75% of the Earth's surface, record much of the Earth's history, and are the repository for the fossil record. Stratigraphy, or the study of the physical and chronological links between rock layers or strata, is closely related to sedimentology. The study of landforms, their processes, forms, and deposits at the Earth's surface is known as geomorphology (and sometimes on other planets). Landscapes are examined to determine how the earth's surface processes such as air, water, and ice can shape the landscape. Landforms are formed through erosion or deposition, in which rock and sediment are worn away by earth-surface processes and transported and deposited in various locations. Distinct climatic settings result in different landform suites. Desert landforms like sand dunes and ergs are vastly different from glacial and periglacial structures found in polar and sub-polar regions. Geomorphologists use maps to visualise the distribution of these landforms in order to better understand their occurrence.