Chapter 2 Flashcards
What are the sections of the earth?
Inner core
-Solid, mostly iron and nickel
Outer core
-Liquid, mostly iron
Mantle
-Semi solid layer of rock that helps transports portions of the overlying crust
Crust
-Solid outer layer of Earth
Is continental crust lighter than oceanic crust?
Yes
Continental crust typically contains a greater amount of lighter elements than oceanic crust of similar volume
Does subtle difference in density influence how continental and oceanic crust of different plates interact?
Yes
What are the probable composition of Ocean and Continental crusts?
Oceanic crust probable composition is basalt
Continental Crust probable composition is granite
What are Plate tectonics?
the large scale motion plates of the Earth’s lithosphere
What is seafloor spreading?
occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge
What is subduction?
takes place at convergent boundaries plates where on plate moves under another and is forced or sinks because of gravity into the mantle
Ocean crust sinks
Continental crust floats
Are tectonic regions complex?
Yes
What are the three types of plate boundaries?
Diverging Boundaries
Converging boundaries
Transform boundaries
What is Diverging Boundaries?
Where the plates move apart
From rift zones
What are converging boundaries?
Where plates collide
From subduction zones, where trenches are produced, or thrusts zones, where mountains are formed
Pressure and friction from subduction melt rock which emerges as volcanoes in cracks along the edge of the oceanic crust
What is transform boundaires?
Where one plate slides past each other in opposite directions
Where is oceanic islands commonly formed?
Along subduction zones
Where are hot spot volcanoes formed?
where plumes of superheated mantle melt through overlying plate
How are series of islands formed?
A series of islands may form as the plate migrates over the hot spot
How are mountains and islands made?
Plate movements can result in vulcanisms, leading to mountain formation on continental crust and island formation on oceanic crust
Hot spot volcanism is another way island can form
As oceanic crust subducts, series of islands or mountains are formed
What is the estimated time the Earth was formed?
~4.5 BY(Billion Years) ago
What is the estimated time Guam was made?
44 MY(Million Years) ago
Is Guam’s Geological History Complex?
Yes
What is Limestone made out of?
Calcium carbonate, it dissolves in water
Explain the Geo Map of Guam
Volcanic formations primarily in S Guam
Limestone formations primarily in N Guam
Formations become exposed through tectonic uplift
Geology influences the regional soils, hydrology, and biology of Guam
Did northern Guam use to have an atoll?
Yes
What reduced carbonate sediment?
Erosion and dissolution
How is an Atoll island formed?
from coral rubble piled up from wave activity
What is climate?
the long term pattern of factors such as temperature, rainfall, day length, and their seasonal changes
the long term atmospheric conditions for a particular area
What is weather?
the shorter term variations in atmospheric factors (wind, humidity, rainfall, etc.)
Is there more rainfall in the north and the east coast?
Yes
Is there less rain in the middle and west of Guam?
Yes
What influences the vegetation of a particular area?
Temperature, water availability, and sunlight
What do regions that have similar climatic conditions have in common?
They have plants with similar growth forms and physiologist (collectively called “physiognomies”)
Different ____________ are defined by their particular climate and physiognomies
Biomes
What do Tropical islands experience?
experience only modest seasonal variation in temp and sunlight
What do islands have within a given year
seasonal variation in rainfall and wind
Rainy season
Dry season
What do many tropical organisms exhibit?
seasonal variation in reproduction, recruitment and migration
What are the 2 common perturbations the tropical pacific islands experience?
El nino and the southern oscillation
What is ENSO?
El Nino ad Southern Oscillation
What is the Southern Oscillation?
Monsoon
When air pressure high over s pacific ocean it was low over Indian ocean -> trade winds blow
When air pressure low over s pacific ocean, it was high over Indian ocean -> wind stops or reverses direction
This seesaw he called the southern oscillation
What is an Monsoon?
wind that reverses direction seasonally, bring rain
India - rain in summer
Some years, monsoons don’t happen -> drought and starvation
Sir Gilbert walker investigated this
What are the Many effects of the ENSO?
Fisheries fail, deserts bloom, typhoons, droughts
What happens in the Normal years (la nina)?
Trade winds push warm water across pacific ( e -> w in n pacific)
usually cold, dry years
Upwelling - cold, nutrient rich water rising from ocean depths in E pacific
Feeds phytoplankton and fish!
Sea level 2 ft higher
What happens in El Nino Years?
Trade winds weaken, may reverse
No upwelling -> no fish
Sea level on w pacific islands drop -> reef exposed, many die
Typhoons form farther east -> Hawaii, tahiti
What are Iguanas?
marine herbivores, eat green seaweeds
What did El nino do to the iguanas and sea lions in the galapagos?
Warm waters from El nino destroyed food supplies
What are Sea Lions?
carnivores, eat fish
What is a tropical depression?
a tropical cyclone with Maximum sustained winds of 38 mph (33 knots) or less
what is a tropical storm?
a Tropical cyclone with maximum 73 mph (63 knots) and a minimum 39 mph (34 knots)
What is a typhoon?
a Tropical cyclone with max, sustained winds of 74 mph (64 knots) or higher
what is a major typhoon?
a Tropical cyclone With maximum sustained winds of 111 mph (96 knots) or higher, corresponding to a category 3, 4, or 5
What does an average sized typhoon release?
releases 2,400 billion kilowatts (KW) of power every day
What is the estimated amounts of tropical storms, typhoons, and super typhoons Guam recieves?
Tropical storm - every 1 - 2 years
Typhoon- every 4-5 years
Super Typhoon- every 50 - 60 tears
52 Tropical cyclones passed within 69 miles from 1945 - 1993
What are the effects of Typhoon on an island’s communities?
Typhoons modify terrestrial Communities by increasing leaf litter and opening forest gaps
Reefs may experience damage from waves and surge
Atolls may become flooded and groundwater from the aquifer may become contaminated with salt
Where does the Pacific Plate move to?
Southeast to northwest
Subducts under the Mariana Microplate
Also includes Uplift
Resulted in Guam moving eastward
What is Oceanic-Continental Converging Boundaries?
More dense oceanic crust subducts under less dense continental crust when the 2 plates converge
What is oceanic-oceanic converging boundaries?
Density of both crust are similar
subduction is determined by factors such as plate size and pressure and friction
Makes volcanoes
Forms trenches
What is Continental-continental converging boundaries?
Both plates usually go up and form mountain ranges
How many plates are on the Earth’s crust?
14 major plates
Where was Guam Originally placed/started?
20 degrees south of its current location and possibly farther west along the Philippine plate
What are the 3 volcanic formation places that dominate southern Guam?
Facpi
Alutom
Umatac
Does temperature on tropical islands depend mainly on altitude?
Yes
What are the 2 sets of factors that shape the Pacific Island environments?
1) Geological nature of the island (High/low; volcanic/continents)
2) Geographic location, rainfall patterns
What are the ocean effects during Normal and La Nina years?
West Pacific
-Low atmospheric pressure
-High sea level
-More rainfall
East Pacific
-High atmospheric pressure
-Low sea level
-Less rainfall
What are the oceans effects during el nino years?
West pacific
-Low sea level
-drought
-high atmospheric pressure
Central pacific
-rainfall
East pacific
-high sea level
-rainfall
-low atmospheric pressure
-thermocline shuts off
Does winds always blow from high pressure areas to low pressure areas?
Yes
When easterly winds/trade winds are strong?
there is little/no rain
When easterly winds/trade winds are weaken
heavy rain
When the traveling winds are strong, they push water across the tropical pacific, making sea level…
2 feet higher in the W pacific than the E pacific
What is the Orographic effect?
Elevation of high islands promotes the condensation of moisture/rainfall
