geography test #3

Depict Earth's interior in cross section, and describe each distinct layer.

Earth's core = inner core + outer core Inner core is solid. (Why?) Outer core is liquid. Core mass = 1/3 of Earth's mass. Core volume = 1/6 of Earth's volume.

Describe the formation of continental crust, and define displaced terranes.

How did Earth's continental crust form? Tectonic activity (powered by internal energy) + Weathering and erosion (powered by the Sun through motion of air, water, and ice) Strain is how rocks respond to stress, and expressed in rocks by folding (bending) or faulting (breaking). • Tension stress causes stretching strain. • Compression stress causes shortening strain. • Shear stress causes twisting laterally strain.

Describe first, second, and third orders of relief, and list Earth's six major topographic regions.

- First order of relief: The coarsest level, consists of continental landmasses and ocean basins. - Second order of relief: The intermediate level, includes mountain masses, plains, lowlands (continental features), mid-ocean ridges, oceanic trenches... - Third order of relief: The most-detailed level, includes individual mountains, cliffs, valleys, hills, and other smaller scale landforms...

List the three types of plate collisions associated with orogenesis, and identify specific examples of each.

- Oceanic plate-continental plate collision orogenesis - Oceanic plate-oceanic plate collision orogenesis - Continental plate-continental plate collision orogenesis

Describe volcanic landforms and distinguish between an effusive and an explosive volcanic eruption.

A volcano forms at the end of a central vent or pipe that rises from the asthenosphere through the crust.

Explain earthquake characteristics and mea-surement, describe earthquake fault mechanics, and discuss the status of earthquake forecasting.

An earthquake is the release of energy that occurs at the moment of fracture along a fault in the crust, producing seismic waves. Seismic motions are measured with a seismometer, also called a seismograph. • Interplate earthquakes are those between two plates, initiated near plate boundaries, and producing nearly continuous linear or curvilinear zones. • Intraplate earthquakes are large damaging earthquakes, located within a single plate, and can occur far from plate boundaries. Earthquake Forecasting • Long-term forecasts (ten to a few thousand years) • Medium-range predictions (a few years to a few months) • Short-range predictions (a few days or hours)

Categorize the various types of mass movements, and identify examples of each by moisture content and speed of movement.

Classes of Mass Movements • In any mass movement, gravity pulls on a mass until the critical shear-failure point is reached. The point is called a geomorphic threshold. • The material can fall, slide, flow, or creep. • A rockfall is a volume of rock that falls through the air and hits a surface. A debris avalanche is a mass of falling and tumbling rock, debris, and soil. • A sudden rapid movement of a cohesive mass of regolith or bedrock that is not saturated with moisture is a landslide. There are two forms of landslide: translational slides and rotational slides. • When soil is saturated, flow will occur. Flows include earthflows and more fluid mudflows. • A persistent, gradual mass movement of surface soil is soil creep.

List and describe several types of river deltas, and explain flood probability estimates.

Delta is the level or nearly level depositional plain that forms at the mouth of a river The mouth of a river is where the river reaches the ocean • Finer materials, such as silty mud and clays, are carried farther and form the extreme end of the deposit.

Explain the process of folding, and describe the principal types of faults and their characteristic landforms.

Folding and Broad Warping • When rock strata that are layered horizontally are subjected to compressional forces, they become deformed. • Folding occurs when rocks are deformed as a result of compressional stress and shortening. • An arch-shaped upward fold is an anticline; the rock strata slope downward away from an imaginary center axis that divides the fold into two parts. A trough-shaped downward fold is a syncline; the strata slope upward away from the center axis. The erosion of a syncline may form a synclinal ridge, produced when the different rock strata offer different degrees of resistance to weathering processes. The hinge is the horizontal line that defines the part of the fold with the sharpest curvature. • Faulting occurs when rocks on either side of the fracture shift relative to the other side. Fault zones are areas where fractures in the rock demonstrate crustal movement. • The fracture surface along which the two sides of a fault move is the fault plane; the tilt and orientation of this plane is the basis for differentiating the three main types of faults: normal, reverse, and strike-slip (or transform), caused, respectively, by tensional stress, by compressional stress, and by lateral-shearing stress. We classify types of faults based on the direction of the relative displacement. • A strike-slip fault is a fault in which the sides of the fault are displaced horizontally. • A fault with vertical displacement is called a dip-slip fault.

Explain the concepts of stream gradient and base level, and describe the relationship between stream velocity, depth, width, and discharge.

Streams create fluvial landscapes through the ongoing erosion, transport, and deposition of materials in a downstream direction • The gradient of a stream is defined as the drop in elevation per unit distance. The river has a steeper slope nearer the headwaters and a more gradual slope downstream. • The level below which a stream cannot erode its valley is base level. Discharge is the streamflow volume passing a point in a given unit of time Discharge is calculated as: Q = w × d × v w is width and d is depth for a specific cross section of the channel, and v is the velocity. Units of discharge: Cubic Length/Time (e.g., m3/s, cfs (cubic feet per second)).

Sketch a basic drainage basin model, and identify different types of drainage patterns by visual examination.

internal Drainage Basin • Moststreamsflowinto the ocean. • Somestreamsdonot reach the ocean. Water leaves the basin through evaporation or subsurface gravitational flow. Such basins are called internal drainage basins.

Describe the nature of coral reefs and coastal wetlands, and assess human impacts on these living systems.

• A coral is a simple marine animal with a small, cylindrical, saclike body called a polyp. • Corals live in a symbiotic relationship with algae. Corals cannot photosynthesize. Algae perform photosynthesis and provide corals with 60% of their nutrition. • Corals secrete calcium carbonate forming a hard and calcified external skeleton. • Skeletons of corals accumulate and form coral rocks. • Coral reefs are biologically derived sediment rocks built upon volcanic seamounts or other submarine features. Coastal Wetlands • Wetlands are saturated with water enough of the time to support hydrophytic vegetation. • Hydrophytic vegetation refers to plants that grow in water or wet soil. • Wetlands usually occur on poorly drained soil. • Two types of coastal wetlands: salt marshes and mangrove swamps • Salt marshes tend to form north (south) of 30°N (S) in the Northern (Southern) Hemisphere (warm to mild climate). • Mangrove swamps form from equator to 30°N (S) in the Northern (Southern) Hemisphere (tropical). Coastal Wetlands Functions • Great productive natural ecosystems • Wildlife habitats • Natural reservoirs and erosion controllers • Act as storm buffers • Natural sewage systems

Describe the three main groups of rocks and diagram the rock cycle.

• A mineral is an inorganic (nonliving) natural compound having a specific chemical formula and possessing a crystalline structure. • A rock is an assemblage of minerals bound together, or a mass of a single mineral, or undifferentiated material, or even solid organic material (such as coal). • Three basic rock types: Igneous (fire-formed, molten material) Sedimentary (from settling out) Metamorphic (altered by heat and pressure)

Describe the depositional landforms associated with floodplains and alluvial fan environments.

• Alluvium: The general term for the unconsolidated clay, silt, sand, gravel, and mineral fragments deposited by running water. • The processes of fluvial deposition occur when a stream deposits alluvium, thereby creating depositional landforms, such as bars, floodplains, terraces, and deltas. Alluvial fans: are prominent cone-shaped fluvial deposits. They commonly occur at the mouth of a canyon where an ephemeral stream channel exits. Characteristics: • Alluvial fans are produced when flowing water abruptly loses velocity as it leaves the constricted channel of a canyon. • Water flows over the surface of the fan and produces a pattern shifting from channel to channel.

Describe the dynamic equilibrium approach to the study of landforms, and illustrate the forces at work on materials residing on a slope.

• As physical factors fluctuate in an area, the surface constantly responds in search of equilibrium. Every change produces compensating actions and reactions. • The balancing act between tectonic uplift and reduction by weathering and erosion, between the resistance of rocks and the ceaseless attack of weathering and erosion. Dynamic Equilibrium Model • Landscapes in a dynamic equilibrium show ongoing adaptations to the ever-changing conditions of rock structure, climate, local relief, and elevation. • Balance between endogenic processes and exogenic processes. • Which processes create landscapes? Which processes destroy or modify landscapes? - Endogenic processes create landscapes. - Exogenic processes destroy or modify landscapes. • Endogenic processes build "initial " landscapes. • Exogenic processes develop "sequential" landscapes. •Slopes • Material loosened by weathering is susceptible to erosion and transportation. • For material to move downslope, the forces of erosion must overcome other forces: friction, inertia (the resistance to movement), and the cohesion of particles to one another. • If the angle is steep enough for gravity to overcome frictional forces or if the impact of raindrops or wind dislodges material, then erosion of particles and transport downslope can occur. A slope is stable if its strength exceeds the weathering and erosion processes (e.g., gentle slope, clay soil). • A slope is unstable if slope materials are weaker than the weathering and erosion processes (e.g., steep slope, sand soil).

Describe common stream channel patterns, and explain the concept of a graded stream.

• Braided rivers: tend to occur in areas with abundant sediment or in the lowest reaches of large river systems. • Single-thread channels: a. Straight rivers: (mountain rivers) tend to occur in headwater areas where gradient is high. b. Meandearing rivers: are more common in lower-gradient areas with finer sediments

Explain the chemical weathering processes of hydration, hydrolysis, oxidation, carbonation, and dissolution.

• Chemical weathering process refers to actual decomposition and decay of the constituent minerals in rock due to chemical reaction, always in the presence of water.

Distinguish between the endogenic and exogenic systems that shape Earth, and name the driving force for each.

• Endogenic system encompasses internal processes that produce flows of heat and material from deep below Earth's crust (Tectonics, Earthquakes, and Volcanism). • Exogenic system involves external processes that set into motion air, water, and ice, all powered by solar energy (River, Landforms, Weathering, Erosion, Oceans, Glaciers).

Describe wave motion at sea and near shore, and explain coastal straightening and coastal landforms.

• Friction between moving air (wind) and the ocean surface generates undulations of water called waves. • Waves travel in groups of wave trains. • A stormy area at sea is a wave generating region of large wave trains. • Erosional coastal processes and landforms - Rugged, high relief, and tectonically active - Such as coastlines of the Pacific Ocean along North and South America • Depositional coastal processes and landforms - Depositional coasts are along land of gentle relief, such as the Atlantic and Gulf coastal plains. - Relatively passive, and tectonically inactive

Describe the chemical composition and physical structure of the ocean.

• Most natural elements and the compounds they form are found in the seas as dissolved solids, or solutes, because water is the "universal solvent." • Seawater is a solution. • Salinityreferstotheconcentrationof dissolved solids. • Sevenelementsaccountformorethan99% of the dissolved solids in seawater: chlorine, sodium, magnesium, sulfur, calcium, potassium, and bromine. • Dissolved gases in seawater (CO2, N2, O2) • Why is the ocean salty? • Salinity = dissolved solids per volume • Worldwide average salinity is 3.5% or 35o/oo (% parts per thousand) • Brackish (salinity < 3.5%) often occurs near landmasses because of freshwater runoff and river discharges, e.g., the Baltic Sea. • Brine (salinity > 3.5%) is associated with high evaporation rates in a nearly enclosed basin, e.g., the Persian Gulf has a mean salinity of 4.0%; along the floor of the Red Sea, the maximum salinity was found to be 22.5%.

Describe the physical weathering processes of frost action, salt-crystal growth, and pressure-release jointing.

• Physical weathering process, also called mechanical weathering, is the process of rock breakage without any chemical alteration.

Draw the pattern of Earth's major plates on a world map, and relate this pattern to the occurrence of earthquakes, volcanic activity, and hot spots.

• Plate tectonics is the theory that the lithosphere is divided into a number of plates that float independently over the mantle and along whose boundaries occur the formation of new crust, the building of mountains, and the seismic activity that causes earthquakes. • Plate tectonics theory describes the motion of Earth's lithosphere. • Convergent boundaries occur in areas of crustal collision and subduction, where areas of continental and oceanic lithosphere meet, crust is compressed and then lost in a destructional process as it moves downward into the mantle. Convergent boundaries form subduction zones, such as off the west coast of South and Central America, along the Aleutian Island trenches, and along the east coast of Japan. • Convergent boundaries also occur where two plates of continental crust collide, such as the collision zone between India and Asia, and where oceanic plates collide, such as along the deep trenches in the western Pacific Ocean. © 2015 Pearson Education, Inc. Divergent Boundaries • Divergent boundaries occur in areas of seafloor spreading, where upwelling material from the mantle forms new seafloor and lithospheric plates spread apart in a constructional process. An example is the divergent boundary along the East Pacific Rise, which gives birth to the Nazca plate (moving eastward) and the Pacific plate (moving northwestward). • Whereas most divergent boundaries occur at mid-ocean ridges, a few occur within continents themselves. An example is the Great Rift Valley of East Africa, where continental crust is rifting apart. © 2015 Pearson Education, Inc. 16 10/20/2015 Transform Boundaries • Transform boundaries occur where plates slide past one another, usually at right angles, to a seafloor spreading center. These are the fractures stretching across the mid-ocean ridge system worldwide. • As plates move past each other horizontally, they form a type of fault, or fracture, in Earth's crust, called a transform fault.

Review the processes and features associated with karst topography.

• The karst topography refers to a limestone (calcium magnesium carbonate) region with a specific landscape of pitted, bumpy surface topography, poor drainage, and well developed solution channels underground, due to chemical weathering.

Identify the components of the coastal environment, define mean sea level, and explain the actions of tides.

• The land, ocean, atmosphere, Sun, and Moon interact to produce tides, currents, waves, erosional features, and depositional features along the continental margins• Tides are complex, twice-daily oscillations in sea level, ranging worldwide from barely noticeable to a rise and fall of several meters. • They are experienced to varying degrees along every ocean shore around the world. • As tides flood (rise) and ebb (fall), the daily migration of the shoreline landward and seaward has significant effects on sediment erosion and transportation.. • Inputs to the coastal environmental include: solar energy, atmospheric winds, climatic regimes, nature of coastal rock and coastal geomorphology, and human activities. spring tide: large neap tide- smaller. quarter moon

Explain the processes involved in fluvial erosion and sediment transport.

• The ongoing interaction between erosion, transportation, and deposition in a river system produces fluvial landscapes. • Erosion: grain particles (sediment) eroded from the riverbed. • Deposition: This material is then transported and deposited in new locations.

Explain the principle of uniformitarianism, and discuss the time spans into which Earth's geologic history is divided.

• The same physical processes active in the environment today have been operating throughout the geologic time. • "The present is the key to the past." • Earthquakes, volcanic eruptions, landslides, mountain-building,... • Earth is thought to have condensed and congealed from a nebula of dust, gas, and icy comets about 4.6 billion (4,600 million) years ago. • Silica and iron are two dominant materials. • During the early stages of the formation, Earth's temperature was so high that silica and iron were all in liquid state. • As temperature decreased, Earth solidified and gravity sorted materials by density.

Define weathering, and explain the importance of parent rock and joints and fractures in rock.

• Weathering processes break down rock at Earth's surface and to some depth below the surface, either disintegrating rock into particles or dissolving it in water. • Parent material is the consolidated or unconsolidated material from which soils develop, ranging from unconsolidated sediments and weathered rock to bedrock. • Joints are fractures or separations in rock that occur without displacement of the sides. • The presence of joints increases both physical and chemical weathering. Why?

Describe Pangaea and its breakup, and explain the physical evidence that crustal drifting is continuing today.

• Wegener concluded that all landmasses migrate, and that approximately 225 m.y.a. they formed one supercontinent that he named Pangaea, meaning "all Earth." • Today, scientists regard Wegener as the father of plate tectonics, which he first called continental drift.