Geomorphology PDF

Geomorphology Fluvial Processes: involve the work of running water, shaping the Earth's surface through erosion, transportation, and deposition. Key concepts include: ○ Stream Channel Forms: The shape of a stream channel can vary, influenced by factors like slope, discharge...

Geomorphology Fluvial Processes: involve the work of running water, shaping the Earth's surface through erosion, transportation, and deposition. Key concepts include: ○ Stream Channel Forms: The shape of a stream channel can vary, influenced by factors like slope, discharge, and sediment load. Common forms include straight, meandering, and braided channels. ○ River Systems: A network of interconnected streams and rivers, including tributaries and main channels. ○ Fluvial Landforms: Meanders: Curved channels formed by lateral erosion and deposition. Meandering landforms consist of the following: Floodplains: a flat area of land adjacent to a stream or river that is subject to periodic flooding. formed by the deposition of sediments, when the river overflows its banks during high flow events. Characterized as broad, flat land that's often rich in nutrients which is good for farming. Oxbow Lakes: Defined as a crescent-shaped body of water that forms when a meander of a river is cut off from the main channel by either erosion or sediment deposition. Happens when a meandering river creates a shark curve which then gets cut off as the two high flow points on each bend merge. Cut Off Channels: Defined as a new, straighter river path formed when a meandering river erodes through a narrow neck of land, bypassing the curve. can lead to the abandonment of the meandering loop and leaving an oxbow lake behind. Levees: Defined as a naturel or artificial embarkments that run parallels to a river or stream, formed by sediment from floodwaters. Provides protection from overflowing onto surfaces. Meander Scars: Defined as remnants of old meanders that have been abandoned by a river. They appear as crescent shaped depressions or basins in the landscape where a former river channel one was. Backswamps: Backswamps are low-lying, wet areas that are typically found behind levees or floodplains. These areas are subject to periodic flooding and are often poorly drained. They can be rich in organic material and support swamp vegetation. Scroll bars: Scroll bars are a series of ridge-like landforms found on the inside curves of meandering rivers. These are formed by sediment deposition, typically in a series of alternating light and dark bands, as the river meanders and deposits sediment on the inner bends.  Terraces: Terraces are step-like landforms that represent former riverbeds or floodplains. They are created when a river cuts down into its own floodplain, often due to changes in climate or tectonic uplift, leaving behind a series of flat or gently sloping surfaces at different elevations. Braided Streams: a stream of a braided style of flow with pockets of sediments everywhere. consists of the following: multiple channels numerous bars and islands steep valley gradient coarse sediments high width to depth ratio These streams occur with these conditions: Stream banks are erodible & non-cohesive Bedload comprises a relatively high % of total sediment load Discharge is flashy (variable) they'll often conclude into floodplains, bars and channels, and terraces. Weathering Processes: ○ Geomorphology is defined as the study of landforms and landscapes. ○ The two different types of process are the following: Endogenic Process: within the earth like a volcano or earthquake. Exogenic Process: on earth's surface including weathering, mass wasting, fluvial, and glacial. ○ weathering process includes: physical changes chemical changes biological changes ex. a rock heating and expanding ○ Chemical Weathering Process: defined as a chemical decomposition of mineral materials. Can be a solution to it is dissassociation of a mineral into its constituent ions in the prescence of water ex. dissolving salt Hydrolysis: defined as a chemical reaction of a mineral with water to form new minerals and dissolved components. Oxidation: defined as a reaction between dissolved oxygen in water and a mineral forming oxides (i.e. iron oxide) In general, chemical weathering process is most affective when: high temp low pH under moist conditions  Materials will form stronger than the original substance. Mass Movement: defined as mass moving down a slope, being rock or sand down a mountainside ○ what influences the slope's stability is: material gradient moisture content ○ It will slide as one unit down the slope given lower moisture content. ○ The flow will be more oriented towards higher moisture content. Glacial Processes: defined as massive bodies of ice, are powerful agents of erosion and deposition, shaping the Earth's landscape over millennia. ○ Glacial Formation Accumulation Zone: The upper part of a glacier where snow accumulates and compacts over time. Ablation Zone: The lower part of a glacier where ice melts or sublimates, leading to mass loss. Equilibrium Line: The boundary between the accumulation and ablation zones. ○ Glacial Erosion Plucking: As glaciers move, they freeze onto rock fragments and lift them out of the bedrock. Abrasion: Rock fragments embedded in the ice scour the bedrock, creating striations and polishing the surface. ○ Depositional Landforms Moraines: Ridges of till (unsorted glacial sediment) deposited by glaciers. Terminal Moraine: A ridge of till marking the farthest advance of a glacier. Lateral Moraine: A ridge of till deposited along the sides of a glacier. Medial Moraine: A ridge of till formed by the merging of two lateral moraines. Outwash Plains: Flat, often sandy plains formed by meltwater streams flowing from the glacier's edge. Kettle Lakes: Depressions formed by the melting of buried blocks of ice. Drumlins: Smooth, elongated hills formed by glacial till. Eskers: Long, winding ridges of sand and gravel deposited by meltwater streams flowing within or beneath the glacier.