Geomorphology is a branch of geography that deals with the study of landforms and the processes that shape them. It is an important topic covered under Paper I of the UPSC examination. The key topics covered under Geomorphology in Paper I include:

1. Introduction to Geomorphology:
- Definition and scope of Geomorphology.
- Importance and significance of studying landforms.
- Historical development of Geomorphology as a discipline.
- Approaches and methods used in Geomorphology.

2. Weathering and Mass Wasting:
- Weathering processes and types: physical, chemical, and biological weathering.
- Factors influencing weathering.
- Types of mass wasting: landslides, rockfalls, slumps, etc.
- Causes and consequences of mass wasting.
- Mitigation measures for mass wasting.

3. Fluvial Landforms and Processes:
- Fluvial processes: erosion, transportation, and deposition.
- River systems and drainage basins.
- River valleys and their characteristics.
- Formation and features of fluvial landforms: river terraces, meanders, oxbow lakes, deltas, etc.
- Factors influencing the formation of fluvial landforms.

4. Glacial Landforms and Processes:
- Glacial processes: erosion, transportation, and deposition.
- Types of glaciers: valley glaciers, ice caps, ice sheets, etc.
- Formation and features of glacial landforms: cirques, U-shaped valleys, moraines, etc.
- Glacial erosion and its impact on landscapes.
- Climate change and glacial retreat.

5. Coastal Landforms and Processes:
- Coastal erosion, transportation, and deposition.
- Formation and features of coastal landforms: cliffs, beaches, spits, bars, etc.
- Coastal processes: waves, tides, currents, and coastal erosion.
- Factors influencing coastal landforms.
- Coastal management and erosion control.

6. Karst Landforms and Processes:
- Karst processes: dissolution, erosion, and deposition.
- Formation and features of karst landforms: sinkholes, caves, karst towers, etc.
- Characteristics of karst topography.
- Factors influencing the formation of karst landforms.
- Human impacts on karst landscapes.

7. Tectonic Landforms:
- Tectonic processes: folding, faulting, and volcanic activity.
- Formation and features of tectonic landforms: mountains, rift valleys, volcanic landforms, etc.
- Plate tectonics and landform development.
- Human interactions with tectonic landscapes.
- Earthquakes and their impact on landforms.

In conclusion, Geomorphology is a vast field of study that encompasses various landforms and processes. Paper I of the UPSC examination covers key topics such as weathering and mass wasting, fluvial landforms and processes, glacial landforms and processes, coastal landforms and processes, karst landforms and processes, and tectonic landforms. Understanding these topics is crucial for analyzing and interpreting the dynamic nature of Earth's surface and its impact on human lives.