CHAPTER 12: EARTHS HISTORY AND INTERIOR Flashcards
How old is earth?
4.6 billion years
How old is the universe?
13.8 billion years
What is the anthropocene?
age of human transformation of earths physical systems
When did the anthropocene start?
1800’s, industrial revolution
Why did CO2 levels in the atmosphere rise?
Burnt coal and petroleum for energy
Why are sea levels rising and becoming more acidic?
Increase in CO2
How much has the sea level risen in the last century?
20cms
How much of earths freshwater run off is used by people?
1/2
How much of mammal biomass is made up of people and domesticated animals?
90%, only 0.1% 10000 years ago
What is a light year?
How long it takes to move at a speed of 300km per second
Edmun Hummel proposed which theory?
Expanding Universe Theory
Galaxies, stars and planets are all formed from?
Dust and gas
Solar System formed how many years ago and from what?
4.5-5 billion years by a nebula
How many planets revolve around the sun?
8
What orbits to the planets move around the sun in?
Elliptical orbits
How many planets is earth away from the sun?
3
What was earths atmosphere formed from?
Gases emitted by volcanoes
How did oceans form?
Water vapour and volcanic emissions condensed out of atmosphere
Example of a photosynthetic organism
Cyanobacteria
What are stromatolites?
Colonies of cyanobacteria, earliest form of life in fossil records
What is the Great Oxidation Event?
oxygen concentration increased, 2.4 billion years, ozonosphere formed
What makes life possible on earth?
Ozonosphere blocking UV Rays
Dinosaurs existed how many years ago?
240 million years
modern humans existed how many years ago?
200, 000 years ago
What are Eons?
largest division of time scales
What eon are we currently living in?
Phamnezobnic eon
What era are we living in?
Cenozoic era
What period are we living in?
Quaternary period
Which Eon accounts for 85% of geologic time?
Precambrian Eeon
Oldest rocks found on earth are how old?
4 million years old
What Epoch are we currently living in?
Holocene or anthropocene
What is the idea of uniformitarianism
present is the key to the past, processes that have shaped landscapes of the past are the same and will shape the future
Principle of Superposition
oldest rock layer at bottom
Hutton’s Unconformities is located at
Siccar Point
define unconformity
an ancient land surface representing a time gap in the normal geological sequence
2 Ways scientists date materials
- Relative Age
2. Absolute Age
What is relative age?
compare age of one object or event with another without specifying how old either is, the order of eevnts
What is absolute age?
specifies age in years!
2 techniques used to determine absolute age
Dendrochronology
Radiometric Dating
What is dendrochronology
tree ring analysis
What is radiometric dating?
assigning ages to material based on radioactive half-life of unstable elements in those materials
Which energy is sustainable and renewable?
Geothermal energy
What are xenoliths?
rocks elevated to earths surface via magma
Most of what we know about earths interior comes from analysis of…
seismic waves
What is a seismic wave?
energy released by earthquakes that travel through the earths interior
What is an earthquake?
sudden shaking of the ground caused by movements of earths crust
What are surface waves?
Travel along/near surface
Cauuses damage
R & L waves
What are body waves?
Pass through earth
P and S waves
2 types of earthquake waves
Surface and Body Waves
Which earthquake wave can travel through the core?
P-Waves
what is the geothermal gradient?
earths interior increasing with depth
how hot is earths core?
6000C
4 FACTORS THAT MAKE EARTH HOT INTERIOR
Friction
Asteroid bombardment
Tidal Forces
Radioactivity
3 Principle lawyers of earths interior
CORE
MANTEL
LITHOSPHERE
What is the radius of the earth?
6371km
Earths inner core is solid or liquid?
SOLID
Which elements are found in earths inner core
Iron and Nickel
What keeps the inner core solid?
compressional forces
Circulating liquid metal which generates earths magnetic field is located in the…
outer core
What is a dynamo?
a device converting the energy of motion to that of an electric current
What is the magnetosphere?
Protects earth from solar wind
How many km does magnetic north move each year?
55km
Temperature of earths mantle
4000-900C
Which portion of the mantle is solid rock, but slowly deforms and flows in great circular convection loops
Lower Mantle
Which portion of the mantle is in solid state, but nearer melting and weak and easily deformed?
Asthenosphere
Which portion of the mantle is rigid and brittle
Lithospheric Manleys
Layers of the mantle from bottom to top
Lower Mantle, asthenosphere, lithospheric mantle
What 2 portions layers are apart of the upper mantle?
Lithosphere and Asthenosphere
2 types of earth crusts
Continental crust
Oceanic crust
Which crust is composed of mainly granite (forms from magma)
Continental crust
Which crust forms from basalt (forms from lava)
Oceanic crust
What is the Moho?
Boundary that separates the crust from the lithosphere mantle
Moho is deepest under which crust?
Continental crust, 70km
Moho is shallowest under which crust?
Oceanic crust, 7km
The lithosphere is broken into how many major plates?
14
What is diastrophism
plates buckle into mountains, bend and warp into hills and break causing earthquakes
What moves the plates?
Convection
Which plate is the largest?
Pacific Plate
Which plate are we on?
North American Plate