molten material works its way to the crust and it might not reach the surface befor it hardens.
magma that reaches the ground surface
mobility of the lava is influenced by high temp (more fluid) lower temp mobility of lava decreases
more silica in the lava
more viscous ( less fluid)
the gases (volatiles) which provide the forces that erupt molten rock from vent
very fluid and allows expanding gases to bubble upwards and excape from vent. Produces lava fountains
highly viscous lava
lava moves up but gases are restricted. It increases in size till they explode
flow in thin sheets or ribbons
contain disolved gases held within molten rock.
composition of gases
70% water vapor, 15% carbon dioxide 5% nitrogen 5% sulfur
form at the surface and are are considered extrusive
green, pyro, fire clastss broken fragments
anatomy of a valcano
begin with a crack onto the surface of the earth as magma moves strongly towards it
path or corridor that the magma travels through before it erupts on the surface opening called the vent
deep walled depression situated at the summit of calcanoes
large more or less circular depression
Broad gently sloping volcanoes made of solidified lava flows.
have grown up from deep ocean floors to form islands.
ex hawaiian island
made of pyroclastic fragments ejected froma central vent .Slopes steeper but not as large than shield valcanoes
Found in flanks and calderas of hawaiian shield valcanoes
made of alternating layer of pyroclastic materals and lava flows.
Slopes intermedient between shield and cinder
ex andes mountains
** essay Living with Valcanoes
growth of an island
effects on climate
In Iceland, Loki of Norse mythology is thought to have been imprisoned underground and blows
lavas and steams through fissures.
Native Americans of the Pacific Northwest
regarded volcanoes as warrior gods, who would throw red hot boulders.
growth of an island
Volcanoes are at times, thought to be associated with destruction, but some effects can be beneficial. Hawaii would not have existed without volcanic activity.
underground heat generated can be helpful if harnessed to power turbines for electricity
effects on climate
valcanoes spewing large amounts of gas and material in atmosphere, reduses solar radiationa and drop in temperature offsetting global warming
** valcanic catastrophies
Pompeii, Italy; Krakatoa, Western Pacific; Mt. Etna, Italy; Mt. St. Helens, U.S. of A.; Fujiama, Japan.
Structures that form from the positioning of the igneous material at depth. They can only be studied after uplifting and erosion
Tabular features that are produced when the magma is injected into fractures.
Tabular features when magma is injected along sedimentary bedding surfaces.
similar to sills but the magma is less fluid
Largest of intrusive igneous body, when magma was formed at depth and then exposed by upliftment and/or erosion
role of heat
Heat increases with depth. Change in temperature with depth is know as the geothermal gradient.
role of pressure
increases with depth as well and is an important factor in melting the rock.
role of volatiles
gases (volatiles) cause the rock to melt at a lower
temperature, similar to salt for melting ice. Their effect is magnified by increased pressure as earlier discussed
Partial Melting and Magma Compositions
Minerals have different melting points as we studied from Bowen’s Reaction Series. As the temperature increases, the minerals with lower melting temperatures in the rock start melting and after they have melted they start rising towards the surface.
Slowly the composition of the magma approaches the composition of the rock from which it was formed and often the melting is not complete. This is known as partial melting
refers to all changes in the original size and or shape of the rock
rocks return to their original shape and size after the releaase of pressure
rocks do not return to their original shape and size after the release of pressure
at the surface the temperature and pressure is low
materials once the forces exceed their strength. This type of deformation
where the temperature and pressure is high at dephts, involve changing the size and shape of the rocks without fracturing
The mineral composition of the rock establishes its strength. Rocks, like basalt, granite, and quartzite that are composed of minerals break by brittle fracture, as opposed to sedimentary rocks which have zones of weakness break by ductile fracture.
rocks are like a book shelf they will break and deform
are formed as a result of volcanic rocks that are bent into series of wavelike undulations
three dimensional plane which divides the limbs of the folds into more or less two equal halfs
Essay 2 types of folds 3 type faults
slip strike fault
when the limbs of the fold dip away from the axial plane, the fold is an
when the limbs of the fold dip towards the axial plane, the fold is a
a rough circular upfoleded structure similar to an anticline
a roughly circular downfolded structure
are fractures in which movement has taken place
vertical movements between the fault plane has taken place
is where the hanging side of the fault move down is relation to the footwall side of the fault
is where the hanging wall side of the fault moves up in relation to the footwall side of the fault.
where horizontal movements between the fault plane has taken place.
two types being Right Lateral Fault and Left Lateral Fault
If there is no shear displacement then the fracture in the rock is called a
the direction of compress stress of a volcanoes
expansion result of tension
process of mountain building
meanign of mountain
coming to being
Form when two oceanic plates converge and one is subducted beneath the other
mountain building along andean-type margins
convergence of an oceanic plate and a continental plate because of subduction of the contiental plate
When two continental plates come together and the are separated by the ocean floor
the ocean floor subducts and brings the two continental plates together which then collide
FAULT BLOCK MOUNTAINS
result of normal faulting where one block is thrust up and the other thrust down.
is defined as the balance or equilibrium of blocks floating on the upper mantle
The erosion of sediments due to weathering may lower the weight of the rocks and they rebound back as the pressure is released. (like removing the weight from a pillow).
geology time scale observed by
major john wesley powell
where did john wesley powell explor that earth is consealed in its rocks
present is the key to the past,
the processes operation on the earth today (earthquakes, volcanoes, erosion, etc.) have been operating on the earth thorough its history
he reverse of uniformitarianism, which means that the processes operating in the past are operating today.
radio activity principles
can establish the age of rocks
ages of rock in the field
based on comparison
the sequence of events that took place
putting rocks in their proper sequence of formation
the study of 2 items
Essay 5 Principles Used to Determine Relative Time
that when material was initially deposited on the surface of the earth, it was deposited in a horizontal fashion. The folding-faulting observed in the rocks, was after its deposition.
the layers below are older than the layers deposited on
top of them. The oldest is at the bottom and the youngest is at the top.
the original sedimentary layer extends laterally until it tapers or thins out at the edges.
the disrupted pattern is older than the disruption which
caused it. When a fault cuts across layers of rocks the fault is younger than the layers that it cuts across.
the fragments included in the host rock are older than
the host rock.
abody of rock intrudes another one, the intruding body of rock is younger than the host rock
a surface that represents the gaps in geologic record.
Is the contact representing missing rock strata. The older rocks were eroded away which were parallel to the bedding surface.
a contact in which the younger strata lie over the older
ones that are tilted or folded.
erosion surface on a plutonic or metamorphic rock has been covered by younger sedimentary or volcanic rock.
by which rocks are similar against one another, can be within reagon a contient or between continent.
able to trace physically the course of a rock unit.
Similarity of Rock Types
Correlation between two rock types can be made on the assumption that the two rock types in two different regions were formed at the same time.
Correlation by Fossils
The fossils succeed one another in a predictable order.
principle of faunal succession
If the same fossils are found between two rock types then a correlation between then can be
Only after the discover of radioactivity have scientists been able to establish
the age of rocks
Establishing the age of the rock using radioactive elements is
the spontaneous necular decay of certain isotopes
Atoms of the same element having different number of neutrons but the same amount of protons.
The time taken by a given amount of radioactive isotope to be reduced by one half.
100g uranium decays to
50g uranium and 50g lead
2 radio activity of a person
how long exposed and intense was exposure
The different isotopic dating methods include
U/Pb, Rb/Sr, K/Ar, Radiocarbon
Curves Used to Establish the Age of the Rock by Comparing The Amount of Radioactive Isotope Remaining in Time to the
Combining relative and numerical ages gives
better perspective regarding the occurrence of geologic events and the ages of materials
numerical dating can also confirm or deny the
observations made by relative dating.
earths age of 4.5 billions years old is much older than
the oldest rock found.
earths age was made on basis of
meteorites and lunar rocks
that the planets and other bodies of the earth solar
system, earth including formed at about the
thin gaseous veil which surrounds the earth and is held together by forces of gravity
Is the state of the atmosphere at any given time.
what the weather comditions are
COMPOSTION OF THE ATMOSPHERE:
composition of the air is not constant. It varies from location to location and from time to time.
Major Components of the atmosphere
nitrogen 78% oxygen 21%
atmosphere variable compoents
include water vapor, aerosol, and ozone
is the weight of the air above. As the altitude increases pressure decreases.
The atmosphere is divided into four layers based on
above the mesosphere and regions of increasing temperatures owing to the absorption of solar energy, outermost layer
above the stratosphere and characterized by
layer immediately above the troposphere and a region with high temperature owing to the concentration of ozone.
lowermost layer and is characterized by decreasing temperatures with height.
all of earth’s energy comes from the sun
the sun is what
The weather at any time during the year is dependent upon
SSP sub solar point
recieves direct energy from the sun
The earth rotates (or spins) on its own axis
the earths journey around the sun
the eath is tilted at an angle of 23.5 degrees
how long does it take the earth to orbit the sun
how many people live in the northorn hemphere
the shortest and longest shortest day
the molecule to molecule transfer of heat
physical mixing involving vertical motion
the transfer of heat to space via electromagnetic radiation
type of light that is used for security systems
is a process where light bounces back from an object like a mirror
produces weaker rays that travels in all directions
reflecting property of a surface ex jewlery snow asphalt
light reaches the earth’s surface and the earth radiates energy back into the atmosphere
Very little of that energy escapes and the energy is trapped in the atmosphere
AIR TEMPERATURE DATA
Data compiled by meteorologists involve minimum, maximum and ranges of temperatures
Daily Mean Temperatures
Temperatures-Maximum and minimum temperatures / 2
Daily Ranges of Temperatures
Daily difference between min and max temp.
averagin daily means
average of monthly means
annual temperature range
differenes of highest and lowest monthly means
Essay Controls of temperature
as it increases the differences in yearly range of temperatures increases. The seasons are more pronounced.
If two cities are at the same location, however, if one is at a higher location than the other, then the city with the higher location, has a more range of temperature. It
could be much colder or warmer.
have a moderating effect on the weather. They can act as beach umbrellas during the summer and as blankets during the winter.
** need examples Land and water
Even though two places are almost at the same latitude, but if one is situated close to a body
of water (Vancouver) and the other is landlocked (Winnepeg), then the one that is situated close to a body of water (Vancouver) will have a mild climate as opposed to the one that is landlocked (Winnepeg), which will have climatic extremes (very cold and extremely warm). E.g. San Francisco (next to an ocean) and Wichita (landlocked