CH2: THE PHYSICAL ENVIRONMENT Flashcards
innermost layer of the earth
solid inner (iron and nickel)
liquid outer (mostly iron)
super hot (5700K)
Core
middle layer of earth
semi-solid layer that helps transport portions of overlying crust
hot liquid inner
solid outer (more viscous and elastic)
rises and expands when heated, descends when cool
Mantle
solid outer layer; lithosphere
14 major plates
plates are buoyed by mantle movement and the thickness and density of the plate
Crust
the constant motion, moving against, away from, or sliding past of plates
large scale motion plates of the lithosphere
Plate Tectonics
denser, thinner, younger crust
Oceanic Crust
lighter, thicker, granite, older crust
Continental Crust
along mid-ocean ridges where new oceanic crust through volcanic activity
Magma emerges from mantle, fills space, cools as moves away from spreading center
ridges in middle of ocean where magma is below, pushes plates apart
Seafloor Spreading
at convergent boundaries where one plate moves under another and sinks into mantle
where oceanic and continental plates meet (oceanic sinks because heavier)
forms a trench
Subduction
submarine depression on the sea floor where two plates meet
Trench
plates collide
form subduction zones (trenches) or thrust zones (mountains
Convergent Boundaries
denser plate sinks (oceanic)
pressure and friction from subduction melt rock which emerges in cracks along the edge of continental crust as volcanoes
Oceanic-Continental Converging Boundary
similar density; subduction determined by plate size
pressure from subduction melt rock which emerges as volcanoes in cracks along edge of oceanic crust
Oceanic-Oceanic Converging Boundary
plates move apart
form rift zones where new crust is made
Divergent Boundaries
plates slide past in opposite directions
Transform Boundaries
What 2 things between plates can melt crust and create earthquakes?
Friction and Pressure
melted rock heats and expands, working its way through cracks and spaces in the overriding crust in water or through continental crust (volcano)
Magma
Where are oceanic islands commonly formed along?
Subduction Zones
areas of volcanic activity from superheated mantle plumes that melt through overlying plate, forming volcano/island
stationary even with moving plate
creates ISLAND CHAINS that MIGRATE over time bc of HIGH MAGMATIC ACTIVITY
Hotspot Volcanism
When were the Mariana Islands formed?
Cenozoic Era
When was Guam formed?
Mid Eocene Epoch
deposited in layers from different lava flows and eruption events
Volcanic (Igneous) Rock
deposited in layers from different erosion processes with particles of varying sizes and crystal compositions
Sedimentary Rock
type of sedimentary rock
growing parts break off and remains of corals and other calcareous animals and plants accumulate as sediments
Limestone
What 2 phases of buildup contributed to Guam’s geological history
Volcanic and Carbonate
No longer volcanically active
Primality submarine volcanism
Guam, Rota, Tinian, Saipan, FDM
Volcanic Phase
Onset coincided with rifting of the Marianas from the West Mariana Ridge
framework and detrital limestone formations
islands submerged, coral grows and deposits, then raised
volcanic base but north was submerged long enough to form an atoll then raised
Carbonate Phase
How was Guam formed?
pacific plate subducted under Philippine plate, causing friction and heat, creating magma to form Guam’s volcanic base
Guam’s oldest volcanic rock in Umatac
Facpi Formation
2nd oldest Guam volcanic rock formation
Alutom Formation
3rd oldest Guam volcanic rock formation
Umatac Formation
2 Northern Major Limestone Types formed by ancient coral reefs and marine deposits
Barrigada Limestone and Mariana Limestone
How atolls are formed
coral rubble piles from wave activity and erodes (making atolls dynamic)
What is necessary for atoll habitability?
Waves have to replenish carbonate sediment that was reduced by erosion and dissolution
sandy, near reef passages, change size but stay in same spot, vulnerable to storms
Type I Islets
Largest and most stable, often inhabited, grows bigger over time, affected by typhoons
Type II Islets
Long, narrow, curved, grow during storms and erode over time, fresh water under, support bigger life forms
Type III Islets
complex, unstable, grow during storms, erode gradually; ex: Cocos Island
Type IV Islets
long term patterns of factors (temp, rain, day-length, seasonal changes)
Climate
short term changes in atmospheric factors (wind, humidity, rainfall, storms, typhoons; extreme - drought, famine)
Weather
What seasons does Guam have?
Wet and Dry
What are 2 things that vary between and within islands?
Rainfall and Temp
What affects temperature on islands?
Mountains (higher altitudes - colder; air rises to cool and release rain on other side)
How do mountains affect rainfall?
windward side gets more rain than sheltered leeward side
What factors shape ecosystems?
island’s geological makeup (high, low, volcanic, coral)
geographic location (rainfall patterns, vulnerability to climate change)
side where winds from ocean climb mountain on one side, cooling air and forming clouds for lusher land
Windward Side
side where wind falls, dry and sucks moisture out of land making it drier
Leeward Side
What defines different biomes?
Climate and Physiognomies
(climatic conditions dictate growth forms and can be similar even if not evolutionarily connected)
What contribute to seasonal variation?
Temp, sunlight, rainfall, wind, and species reproduction, recruitment, and migration
(certain seasons allow for certain fruits to grow or fish to come and turtles to hatch)
2 Common perturbations in tropical pacific islands
El Nino & Southern Oscillation
Typhoons & Hurricanes
Atmospheric pressures change between the Pacific and Indian Oceans, weakening or reversing trade winds (Southern Oscillation), so warm water isn’t pushed West and pools in the middle of the Pacific, warming and preventing upwelling in the eastern Pacific
Effects: less rain in the western pacific (india, indonesia, aus; droughts, fires, famine) and more rain in the eastern pacific (peru; floods, failed fisheries, typhoons)
El Niño/Southern Oscillation
Stronger trade winds push warm ocean water from the Pacific even further west, causing an increase in the upwelling of cold, nutrient rich water in the eastern pacific
La Niña
giant whirlwinds with powerful winds and heavy rain that form over warm ocean waters that spin from coriolis effect.
Typhoon/Hurricanes
typhoons/hurricanes that spin counterclockwise occur in the ___________ __________
Northern hemisphere
typhoons/hurricanes that spin clockwise occur in the ___________ __________
Southern hemisphere
tropical cyclone in western pacific
Typhoon
tropical cyclone east of international date line; Atlantic ocean
Hurricane
tropical cyclone in southern hemisphere and indian ocean
Cyclones
tropical cyclone with max winds of 38mph (33 knots) or less
Tropical Depression
tropical cyclone with max winds of 39-73 mph (34-63 knots)
Tropical Storm
tropical cyclone with max winds of 74mph (64 knots) or higher
releases ridiculous amount of energy over miles
gains strength from warm water (weakens over land)
Typhoon
tropical cyclone with max winds of 111 mph (96 knots) or higher with a 3-5 category on Saffir-Simpson hurricane wind scale
Major Typhoon
How often does Guam have tropical storms?
1-2 years
How often does Guam have weaker typhones?
4-5 years
How often does Guam have super typhoons?
50-60 years
