Geomorphology and Landforms Lecture Notes PDF

# Geomorphology and Landforms ## Introduction - **Geomorphology:** The study of the Earth's surface features and their formation. - **Geomorphic Processes:** Changes in the configuration of the Earth. - **Endogenic forces:** Internal forces that build up landforms. - Examples:...

# Geomorphology and Landforms ## Introduction - **Geomorphology:** The study of the Earth's surface features and their formation. - **Geomorphic Processes:** Changes in the configuration of the Earth. - **Endogenic forces:** Internal forces that build up landforms. - Examples: - Himalayas: continuously increasing, Endogenic>Exogenic - Aravalis: continuously decreasing, Exogenic>Endogenic - **Exogenic forces:** External forces that wear down landforms. ## Endogenic Forces - The pressure within the Earth, also known as internal forces. - **Energy sources:** - Radioactive decay - Tidal friction - Primordial heat - Convection currents (Arthur Holmes) ### Endogenic Processes - **Diastrophism:** Processes that move, elevate, or build up the Earth's surface. - **Orogenic:** Mountain building processes. - **Epeirogenic:** Changes except mountain building, like uplifting or subsidence of large areas. - **Earthquakes:** Shaking of the Earth. - **Plate tectonics:** Movement of the Earth's tectonic plates. - **Volcano:** Openings or vents where lava or magma erupts. ## Exogenic Forces - Due to exogenic forces, cause wearing and tearing of landforms. - **Gradation:** Wearing down of relief features of the Earth. ### Exogenic Processes - **Denudation:** The collective term for exogenic forces that wear down landforms. - **Exogenic Agents:** Running water, wind, waves, and groundwater. - **Ultimate source of energy:** Sun ## Denudational Processes - **Weathering:** The breakdown of rocks, building materials, etc. - **In Situ:** Breakdown occurs in place. - **Ex Situ:** Breakdown products are transported away from the site. - **Types of Weathering:** - **Chemical weathering:** Breakdown due to chemical reactions. - **Physical/Mechanical weathering:** Breakdown without chemical change. - Examples: frost wedging, thermal expansion and contraction. - **Biological weathering:** Breakdown due to the actions of living organisms. - **Mass Movements:** Movement of weathered material downslope. - **Main force involved:** Gravity - **Types of Mass Movements:** - **Fast:** Landslides, avalanches, earthflows. - **Slow:** Creep, solifluction. ## Landforms - **Erosional landforms:** Created by the erosion of rock. - **Depositional landforms:** Created by the deposition of sediment. ### Landforms Created by Rivers - **Youthful stage:** V-shaped valleys, gorges, canyons, waterfalls, rapids, entrenched meanders. - **Mature stage:** Meanders, oxbow lakes. - **Old stage:** Floodplains, deltas, and levees. - **Erosional features:** - V-shaped valleys. - Gorges. - Canyons. - Waterfalls. - Potholes. - Plunge pools. - River terraces. - Incised meanders: Cutting into bedrock because of uplift or a lowered base level. - **Depositional features:** - Floodplains. - Deltas. - Oxbow lakes. - Alluvial fans. ### Landforms Created by Glaciers - **Erosional features:** - Cirque: Bowl-shaped depression at the head of a glacial valley. - Arête: Sharp ridge between two glacial valleys. - Horn: Peak formed by the intersection of several cirque glaciers. - Hanging valley: Smaller glacial valley that enters a larger valley at a higher elevation. - Glacial valley: U-shaped valley formed by glacier erosion.. - Fjord: Sea water entering a glacial valley. - **Depositional features:** - Moraine: Accumulations of rock debris deposited by a glacier. - Eskers: Long winding ridges of sand and gravel deposited by glacial meltwater. - Drumlins: Egg-shaped hills of till deposited by glacier erosion. - Outwash plains: Flat plains of sand and gravel deposited by glacial meltwater. ### Landforms Created by Groundwater - **Erosional features:** - Sinkholes: Depressions formed when soluble rock is dissolved by groundwater. - Dolines: Large sinkholes. - Lapies: Rough, pitted surface formed by chemical weathering. - Uvalas: Depressions formed by the merging of multiple dolines. - Limestone pavements: Smooth, flat surfaces of limestone exposed by weathering. - **Depositional features:** - Stalactite: Icicle-shaped deposit hanging from a cave ceiling. - Stalagmite: Column-shaped deposit rising from a cave floor. - Pillar: Stalactite and stalagmite that have joined. ### Landforms Created by Sea Waves - **Erosional features:** - Cliff: Steep, rocky slope facing the sea. - Caves: Hollows carved into cliffs by wave action. - Stack: Isolated column of rock left standing after a sea cave collapses. - Arch: Natural bridge formed by erosion through a headland. - **Depositional features:** - Beaches: Accumulation of sand and pebbles along a shoreline. - Dunes: Mounds of sand formed by wind action. - Bars: Submerged ridges of sand running parallel to a shoreline. - Barrier islands: Narrow islands running parallel to a coast. - Spits: Elongated ridges of sand extending from the coast into a bay. ### Landforms Created by Wind - **Erosional features:** - Pediplains: Flat plains formed by wind erosion. - Playas: Dry lake beds in arid regions. - Mushroom rocks: Rocks shaped like mushrooms by wind erosion. - Pedestal rocks: Rocks with a narrow base and a wider top, formed by wind erosion. - **Depositional features:** - Sand dunes: Mounds of sand formed by wind action. - Barchan dunes: Crescent-shaped dunes with horns pointing downwind. - Longitudinal dunes: Long, narrow dunes with their crests aligned parallel to the wind direction. - Transverse dunes: Dunes with crests perpendicular to the wind direction. - Parabolic dunes: U-shaped dunes with horns pointing upwind. - Seif dunes: Long, narrow dunes with their crests aligned parallel to the wind direction. ## Notable Landforms - **Horn:** A glacial landform formed by the intersection of three or more cirques. - **Lapie:** A karst landform, characterized by a rough, pitted surface formed by the dissolution of limestone by groundwater. - **Oxbow lake:** A meander that has been cut off from a river. - **Stack:** An erosional landform, a column of rock left standing after a sea cave collapses. - **Stalactite:** A depositional landform, an icicle-shaped deposit hanging from a cave ceiling. - **Drumlin:** Glacial landform, an egg-shaped hill of till deposited by glacier erosion. - **Alluvial fan:** Depositional landform formed when water flows out of a mountain canyon onto a plain and deposits sediment. - **Barrier islands:** Depositional landform, a narrow island running parallel to a coast. - **Seif dunes:** A type of sand dune elongated in a direction parallel to the prevailing wind direction. ## River Meanders - Most rivers meander in their mature stage. - The only river that meanders in its youthful stage is the Jhelum River.