Human and earth interaction Flashcards
What is the equation for the world population growth rate?
WPGR = (BR - DR) *100%
What was the growth rate in 1900 vs 1960 vs today?
1900 - 0.8%
1960 - 2.6%
Today - 1.05%
Define what doubling time means
this is the time required to double a human
population at a given growth rate.
What is the rule of 70?
Population doubling time = 70 divided by growth
rate.
At world growth rate of 1.05% 70/1.05 = 67 yrs to double the population.
Define non-renewable resources
Resources that cannot be renewed within a humans lifespan are considered to be non-renewable.
What are some ways we can get more use out of non-renewable resources
Mines for uranium, potash, and copper (take millions of years to form)
We can recycle them though to make it more reusable
Fracking to recover more oil from the ground
define feedback loop
outputs (e.g., more sewage waste)
influence the performance of the system (e.g., more
sewage waste getting into drinking water, more
disease)
Earth as a ‘closed system’ with feedback
loops as resource availability changes,
Gaia hypothesis (proposed by James
Lovelock in the 1980s)
Define positive feedback loop
increases a quality of the system
define negative feedback loop
Dampens a quality of the system, keeps the
system more stable
What are the 6 geological eons?
Beginning: Hadean, Archean, Proterozoic, Paleozoic, Mesozoic, Cenozoic.
The first 3 are contained in the Precambrian eon and the last three are contained in the Phanerozoic eon.
How are the boundaries between the eons, eras, periods determined?
Events such as new fossils, disappearance of fossils and major events like meteor impacts
How do geologist reconstruct earths geological history?
They study the rock record: stratigraphic record and fossil record
Define Stratigraphic record
the layers of
rock and their relationships to one
another
Define formation
A formation is a rock layer of the same rock type * or group of associated rock layers that occur over a larger
area and have a specific geologic age
Define contact
The surface/ boundary between 2 formations
Define strata
Layers of sedimentary rock
Define Stratigraphic column
a vertical cross-section where the rock
layers are divided into stratigraphic formations.
In order to understand the history of a rock, geologists use several geological principles. What are the 8?
- Uniformitarianism
- Original horizontality
- Law of superposition
- Lateral continuity
- Cross-cutting relationships
- Fossil succession
- Inclusions
- Unconformities
Define uniformitarianism
processes operating at the present are the same processes that
have operated in the past.
define catastrophism
was an earlier theory, generally not
the way Earth’s surface has evolved but catastrophic
events have been important sometimes.
* For example, Asteroid impacts
Define Original horizontality
beds of sediment deposited in water were formed as
horizontal or nearly horizontal layers
This implies that a horizontal attitude is normal for most sedimentary beds/rocks
Attitude means
orientation
Sedimentary rocks that are not horizontal have been subjected to some other geological process such as
folding or faulting
Define superposition
within a sequence of undisturbed sedimentary rocks,
the layers get younger going from the bottom to top
Define the principle of lateral continuity
Usually, sediments are deposited as continuous sheets * Erosion can remove sediments, making them discontinuous
even though they originated as one continuous unit
Define cross-cutting relationships
Younger features cut across older features
* Faults, dikes, and erosion, must be younger than the materials that is faulted, intruded, or eroded
Define the principle of fossil succession
Fossils are the preserved remains or
traces of organisms from the past
* A geological time span can be
identified by its suite of fossils since
different organisms lived during
certain time periods, and follow one
another in an accepted and
recognized order based on decades of
research
* E.g., Trilobites lived only in the early
Paleozoic time & Ammonoids Late
Paleozoic & Mesozoic.
Define inclusions
Inclusions are fragments of a rock unit that are found
enclosed within another rock unit.
The rock that supplied the rock pieces must be older than the
rock unit within which the pieces are enclosed.
Define Unconformities
- Rock layers that are deposited over time mainly without
interruption are said to be conformable beds. There is no gap in
time in the age of the beds. - Unfortunately, there is no place on Earth where there is a
continuous sequence of conformable beds of all of Earth’s
history. - An unconformity represents a gap in
- time between preserved beds:
1. Due to erosion and/or,
2. Lack of material resulting in no
deposition.
What are the 3 types of unconformities
angular unconformities, non-conformities, and disconformities
Define angular unconformity
Where a tilted bed underlies a horizontal bed
Define nonconformity
where a
break in time occurs between
older metamorphic or igneous
rocks and younger
sedimentary rocks.
Define disconformity
where gap
in time is not readily
apparent with horizontal
sedimentary beds on either
side of the unconformity
Stratigraphic column
a
vertical cross-section
where the rock layers are
divided into stratigraphic
formations.
The rate of radioactive decay is measured in?
Half life
Each radioactive element has a ____ half-life –
this is how we can get _______ dates for
absolute dating measurements!
set
accurate
When radioative minerals crystallize the radioactive elements begin to decay and form ____ ________
New elements
When uranium undergoes radioactive decays it becomes which element
lead/Pb
What type of eleemtn would be used to determine the age of a rock that came from a long time ago vs more recently
Uranium for long periods or time, carbon 14 for shorter periods of time
Why is zircon useful for uranium/lead dating?
When zircons form igneous rocks they do not incorporate lead, only uranium. We can tell the age of the roc by the quantity of lead that decayed from the uranium, which would be stuck in the zircon rock.
Absolute ages vs relative ages
Absolte is exact numbers like 65 million years ago
Relative ages is saying this unit is older than that unit
What does chronological time scale refer to? what does hierarchical time scale refer to?
Chronological - absolute time
Hierarchical - relative time
The hadean, Archean and Proterozoic is often grouped together with what term?
Precambrian
The phanerozoic consists of which 3 eras?
Paleozoic, Mesozoic, and Cenozoic
How many billions or years ago did the big bang occur
13.6 Ga
How many billions of years ago did earth and other planets begin to form?
4.6 Ga
Describe the hadean eon
Volcanic eruptions releasing gases
Layers of Earth began to form, core formed by gravity
pulling Fe (iron) to the center of Earth (the iron
catastrophe)
First evidence of the hydrosphere
Describe the Archean eon
Primordial soup - hypothesis - lightening,
UV react with gases to begin life
meteorite impact craters - special
environments with water, heat, good place
for life to begin
asexual reproduction
Mainly methane and ammonia atmosphere
Continental crust solidifies - cratons
Describe the Proterozoic eon
Life is aquatic
Oxygen increasing in atmosphere and ozone layer formed
sexual and asexual reproduction
Cratons joined together to form continents and continents formed together to form supercontinent(Rodinia)
formation of rich ore deposits (black smokers)
Glaciation occurs leading to mass extinction
Describe the Paleozoic era
first hard shelled animals
oxygen increased in the atmosphere
Cambrian explosion(explosion of life)
