Earth Systems – Final Vocab CHAPTER 16: FLUVIAL PROCESSES Levees – Natural barriers that can trap all the sediment, provide a false sense of security and make floods last longer STREAM STRUCTURES Consequent Streams – Flow follows underlying rock structure Subsequent Streams – Flow follows line or zone of rock weakness. Excavate their channels along an outcrop of weak bedrock. Antecedent Streams – Flow is impacted by land uplift but maintains course. The uplift is so slow that it gives the stream time to erode into it, maintaining its original course DRAINAGE PATTERNS Dendritic – Branching tree roots, most common. Happens because the subsurface geology is homogenous and has similar resistance to weathering, so there is no apparent control over the direction the tributaries take. Trellis – Develops in folded topography. “leaf-leap” structure. Radial – Develops around a central elevated point, common to volcanoes. Centripetal – Flows toward a central depression, typical in basins. Base level - the lowest point to which it can flow, often referred to as the 'mouth' of the river. Downcutting – Streams cut into the streambed using the hydraulic power of the moving water. Knickpoints – Steeper irregularities in the channel that are common to downcutting. I.e. Steep waterfalls. Valley widening – As the stream sways from side to side, it erodes the outside and deposits on the inside. Stream becomes more meandering. Valley lengthening – Either by head erosion (cutting into the interfluves) or by delta formation. Stream capture – Stream A is stronger and approaching Stream B, which is perpendicular. Stream A cuts into Stream b and forms an elbow, the bottom of stream B is the “beheaded stream” Delta – Landform that is created at the mouth of a river where the river flows into an ocean. Yazoo – A tributary stream that runs parallel to a larger river, which it eventually joins. Right next to it, in the same floodplain. Are obstructed from united with the main river temporarily by natural levees. Stream Rejuvenation – Uplift causes streams to flow faster and provides renewed energy for downcutting. Theories of Landform Development – Davis’ Geomorphic cycle – A cycle of youth, maturity, old age, and rejuvenation. CHAPTER 17 : KARST Carbonic Acid - Mild acid formed when carbon dioxide dissolves in water. Underground water is basically a weak solution of carbonic acid. Dissolution: Removal of bedrock through chemical action of water; includes removal of subsurface rock through action of groundwater. Particularly effective on carbonate sedimentary rocks, especially limestone. Caverns: Large opening or cave, especially in limestone; often decorated with speleothems. The largest of these openings are usually more expansive horizontally than vertically, indicating a development along bedding planes. Meaning they’re rectangular and are found anywhere there is a massive limestone deposit. Speleothem: A feature formed by precipitated deposits of minerals on the wall, floor, or roof of a cave. Water leaves behind the compounds (principally carbon dioxide and calcite) it was carrying in solution. Stalactite – Tight to the ceiling Stalagmite – Projecting upward from the cavern floor. Karst: A rugged hilly landscape that has been shaped almost entirely by solution action in limestone formations. The most common features of karst landscapes are sinkholes, which occur by the hundreds. -Karst regions do not have surface drainage. Most rainfall and snowmelt seep downward along joints and bedding planes, enlarging them by dissolution. Surface runoff that does become channeled does not usually go far before it disappears into a sinkhole or joint crack Sinkholes (Aka Dolines): A small, rounded depression that is formed by the dissolution of surface limestone, typically at joint intersections. Their sides generally slope inward at the angle of repose (usually 20 to 30 degrees) of the adjacent material. Collapse doline: A sinkhole produces by the collapse of the roof of a subsurface cavern. These may have vertical walls or even overhanging cliffs. Uvala: A chain of intersecting sinkholes; in many cases, sinkholes evolve into uvala over time. Kind of looks like a retarded valley. Tower karst: Tall, steep-sided hills in an area of karst topography. Disappearing streams: Stream that abruptly disappears from the surface where it flows into an underground cavity common in karst regions. Swallow holes: The distinct opening at the bottom of some sinks through which surface drainage can pour directly into an underground channel. HYDROTHERMAL FEATURES Hydrothermal activity: The outpouring or ejection of hot water, often accompanied by steam, which usually takes the form of either a hot spring or a geyser. Hot spring: Hot water at the Earth’s surface that has been forced upward through fissures or cracks by the pressures that develop when underground water has come in contact with heated rocks or magma beneath the surface. Geyser: A specialized form of intermittent hot spring with water issuing only sporadically as a temporary ejection, in which hot water and steam are spouted upward for some distance. The basic principle of geyser activity involves the building up of pressure within a restricted subterranean tube until that pressure is relieved by an eruption. Fumarole: A hot spring that lacks water. A hydrothermal feature consisting of a surface crack that is directly connected with a deepseated source of heat. The little water that drains into this tube is instantly converted to steam by heat and gases, and a cloud of steam is then expelled from the opening. CHAPTER 18 : DESERTS Arid – Severe lack of water. They look sandy, clear skies, shady. Interior Drainage - a drainage system whose waters do not continue to the ocean either on the surface or underground, but evaporate within the land area. Exotic Stream – Permanent streams in dry land. It crosses a desert as it flows to the sea, or any stream which derives most of its water from the drainage system of another region. Alluvial Fan - are fan shaped sediment deposits formed at the foot of mountains in the desert valley or basin--if there is a coalescence of alluvial fans an apron of sediment called a bajada is formed Playa – A dry flat lake bed that forms after abundant rainfall in desert basins. They are present for a few days because of evaporation and infiltration. Inselberg – Isolated landforms that remain after erosion, they look like rocky islands. Bornhardt – A type of inselberg, composed of highly resistant rock. Pediment – A gently inclined bedrock platform, made by erosion instead of deposition Differential Erosion – Occurs when some parts of a rock weathers at different rates than others. For example, wave action pounding on limestone cliffs erodes the cliff lower down faster than the top of the cliff. Scarp – Resistant layers that stick out, causing a step-like configuration Mesa – tabletop-like structure that protects what lies beneath it. Piedmont zone – Any zone at the foot of a mountain range. Erosion Load Suspended load – Suspended wind blown particles, consists of silt or clay size particles which can cause dust storms. The deposition of the suspended load can form large deposits which lack layering called loess Aridisols – Soils found in dry location. Light in color, have a thin nutrient, crumby, and have a poor A horizon. THREE DESERT LANDSCAPE SURFACES Ergs – A large, relatively flat area of desert covered with wind swept sand with little or no vegetative cover. Class “sea of sand” image of deserts. Regs – aka Desert Pavement. Stony desert, often with ventifacts. Hamadas – Clear bedrock with little loose material. Hard, rocky, little sand. Deflation – The removal of rock waste from the land by wind. Basically dust/sand being blown around. Abrasion – Wind particles eroding the surface. Aka Sandblasting effect. Sand dune – A mound of sand Types of Dunes Barchan Dunes – Crescent shaped, Outer curve facing against wind. It reflects the direction and velocity of the windflow. Transverse Dunes – Straight rows of dune perpendicular to wind. Kind of like waves being pushed by the wind. Stardunes – Star shaped. Probably shaped by multiple wind directions. CHAPTER 19 : GLACIERS Geologic Epoch – A span of time smaller than a period but larger than an age, on the geologic time scale. geologic history of the earth shows repeated glacial epochs followed by period of retreat (interglacials). ~1/3 of the earth was covered with ice over a mile thick. We are currently in an interglacial phase. the last ice age was during the Pleistocene epoch, beginning 1.2-2 million years ago and ending about 10,000 years ago and marking the beginning of the Holocene epoch. Contemporary ice sheet is limited to interior Greenland and Antarctica Glaciers account for about 7% of all surface erosion currently occurring. Snowflakes ( Granular snow ( Neve (Firn) ( Glacier Ice TYPES Continental Ice Sheets – SHEETS OF ICE. Glaciers which cover large non-mountainous areas of the continents Alpine Glaciers – RIVERS OF ICE. A highland glacier that flow slowly down a valley in a mountainous region like a river of ice. Occupying individual valleys below the level of adjacent peaks. Highland Ice Fields – Unconfined sheets in high mountain areas, submerges all adjacent topography except the occasional nunatak, rocks that stick up). Cirque – Glacier filled bowl-shaped depressions within mountains. Aka Firn field. Accumulation zone – Snow added Ablation zone – Snow melted/evaporated Stillstand - Aka Firn Line. Accumulation = Ablation. Crevasse – A huge crack formed by to glaciers colliding. Also if a glacier accelerates, it can cause extension and form a crevasse. EROSION Erosion is proportional to mass of ice and speed of advance. Erosional debris is transported and deposited in moraines. Two ways glaciers can erode, plucking or abrasion. Plucking – Loosens bedrock by ice and plucks it from ground. Abrasion – Mechanical scraping of a rock surface by friction between glacier and bedrock. Lateral moraine – Sediments deposited on sides of glaciers Medial moraine – Two glaciers meet up and their lateral moraines meet up in the middle. End moraine – Current end of glacier Terminal moraine – Marks the furthest advance by glacier POST GLACIAL FEATURES Lakes everywhere in places that have been glaciated. Glacial erratic – A piece of rock that was carried by a glacier which differs from other rocks native to the area. Like a big ass boulder in a forest. Kettle – A depression in glacial drift, formed by the melting of a detached block of stagnant ice that was buried in the drift. A sediment-filled body of water. Kind of like a tiny lake, spotted around landscape. CHAPTER 20 – COASTAL PROCESSES ENERGY OF WAVES The larger the body of water, the greater it’s land-shaping power Waves – Generated by friction of wind over water. Water movement diminishes with depth Tsunamis – Caused by earthquakes (Waves are caused by wind/fetch) Wave Refraction – Waves changing direction as they reach shore. Straighten irregular headlands, creating it into sand. Makes beaches straight. Wave height – Distance between crest and trough Wave length – Distance between crests or between troughs Swells – Long-wavelength waves Fetch – distance that the wind blows over an amount of water Wave break – When the waves over steepen and become unstable. Happens when the ratio of wave height to wave length is greater than 1:7. Plunging waves – Surf-able waves. Indicate a steep shoreline. Like at Point Pleasant Spilling waves – Indicate a shallow slope. Just spill over shore. Headland Erosion – Creates arches and stacks Headland (Irregular shore) ( Arches ( Stack ( Skerry (rock in the sea) Cut Notch – Cut in the bottom of a rocky shoreline, eroded by waves. Marine Terrace – Formed when a wave-cut platform is tectonically uplifted above sea level. Stream Outflow – Stream flowing into ocean through delta provides most sediments that is moved around by the coastal water. Longshore currents – Movement of water parallel to the shore. Longshore drift – Zigzag movement of particles because of longshore currents. Barrier Island System – A long, narrow sandbar built up in shallow offshore waters. Sometimes few hundred meters off coast, but often several km at sea. Lagoons – In-between land and barrier island Coral coasts – Coasts covered with coralline formation. Nearly all islands have them. Barrier Reef – A ring of coral floating around a central volcanic peak. Atolls – The lagoon surrounded by a barrier reef once the volcano sinks down.