just a reminder again about the narrated
lecture
as we've said in the past hopefully
you'll have read through the chapter
ahead of time here
or that you'll read through it after the
narration just to get again
some of the examples that maybe we don't
cover or get some more of the details
uh they're not presented here in this
lecture presentation
so in this chapter we're going to move
away from
some of the policies in terms of
population growth or
the interaction with our living systems
and we're going to focus more on the
abiotic processes more
abiotic structures and in this one we're
going to focus particularly on
some of our resources of the world
around us so looking at things like our
soils our minerals
and how they're going to influence how
we survive on this planet
so one thing you just kind of consider
in the very beginning on the end of the
last chapter we mentioned
the idea about moving from fossil fuels
uh or coal even something like that to
electricity
we might think that moving away from a
vehicle using fossil fuels would be a
good thing
especially going over to something using
maybe solar energy or
electricity in general but we have to
think about
all different aspects when we're looking
at this conversion from fossil fuels to
maybe a electric vehicle is it still
environmentally friendly
and you'll see in the very first part of
the chapter here this little uh brief
example about this conversion and it
talks about how
an electric vehicle or a hybrid vehicle
may actually be just as harmful to our
environment because that this system
that we're creating
in terms of more efficient vehicles
is going to relying on some very
finite resources some very rare earth
minerals that do not have large supplies
of
and that we run out of these supplies
what do we do in terms of maintaining
that system
we also think about the fact that the
mining for the supplies the mining for
these resources
what effect does that have on our planet
as a whole is it worth it to go through
and have this conversion is it worth it
to
deplete those resources that maybe are
again already in a very finite amount
now we think back to the original
source of where all these processes
these resources
everything on our planet where it's come
from keep in mind when we think about
this in terms
of matter we have that the
law of conservation of matter whatever
is here is here
we can't get any extra matter we can't
destroy it we just transform it from
form to form
and that will go all the way back to our
formation of earth
when earth and all the other planets in
our solar system
came to be it was all about this
cloud of cosmic dust coming together and
that as
this cloud of dust essentially starts to
settle out
and we start to get this solid form of
our planets and we get this form of our
sun
forming we are eventually left with all
of our available resources
and all the geological history that has
produced us
for the planet that we have now this
formation of our planet
in terms of earth actually going through
and solidifying and becoming
earth as we kind of know it today with
all this distribution of materials
happened about 4.6 billion years ago
now in this life of our planet
it doesn't sound like a very long time
but think about how long humans have
been on the planet
humans themselves as a species have been
around on the planet about two hundred
thousand years
so four point six billion years ago is
when all the resources that we depend on
today
were essentially coming into existence
force they were being placed in certain
formats they would be in place and
availabilities
and as we fast forward first billion
years the
point about 3.5 billion years ago when
life first starts to form on our planet
and all these resources are coming into
shape a lot of our fossil fuels a lot of
our
reserves of natural gas
our minerals that we look at in terms of
our different elements that are out
there
these are all things again that were
determined based on this initial coming
together of
all this cosmic dust creating our planet
our sun
all of our solar system we have around
us
so as our earth came into existence 4.6
billion years ago we're going to create
this certain configuration
and we'll start here in the core and the
core itself
is the innermost part of our planet and
this essentially is a
large supply of nickel and iron
and we have the solid core in the very
middle and then we have a liquid core
a little bit further out now we're going
to show a little demo
a little uh demographic here in just a
minute
that looks at kind of relative size but
essentially when you're looking at this
representation and it's not related to
scale here as much
you're going to find that the core
itself is not that great of an area it's
pretty small
even the inner core with the more liquid
counterpart
is not that great as you move out here
into our mantle which essentially is now
the area above the core which is this
molten rock or the magma
this is what's going to give rise
eventually to the crust
which essentially is where we live on
our planet
now the crust itself as this solidified
area that's kind of this crumbly and
cracking
layer is actually what is part called
the lithosphere
the lithosphere is where we have the
solid mantle so the
the rock beneath our feet essentially
and then
includes all the crumbling crusts above
it
that has been pushed further and further
up
now even though that the lithosphere
contains part of the mantle
this area below that what's called the
asthenosphere
also includes part of the mantle the
lithosphere includes the solid portion
the asthenosphere is now considering
part of this
liquid portion and so this is the area
again it's located
on the outer part of our mantle but it's
a lot more of a
semi type molten structure it's a lot
more flexible
and this is what's going to influence a
lot in terms
of how our environment how our crust
itself this outermost layer
is going to interact with these bottom
layers here so you've got your molten
layer of the manta in the middle here
the mantle but right there as you come
into this outermost layer of the mantle
that's still somewhat liquid this
semi-liquid area the asthenosphere
then leads into this more solid upper
mantle which will give rise to our
layers of crust beyond that so we're
looking at the
asthenosphere here we can see that this
is the outermost part of the mantle
that's still composed of a
somewhat semi-molten magma
but the lithosphere is this outermost
brittle layer
and it includes this solid layer of the
mantle and the brittle layer which we
think about
as the pteropharma or the soil beneath
our feet
so again in terms of representation you
can see that the mantle and the outer
core
do expand at quite a great distance in
terms
of overall thickness but when looking at
the lysosphere
we're living on it's only 100 kilometers
thick that's a very thin part of the
overall
conditions that we see making up our
planet
so we look at this structuring of our
planet going looking at the different
levels and
think about the influences you're going
to find that the geology on
earth consists of three main cycles
we are looking at the tectonic cycle so
tectonic cycle here we're looking at
things in terms of
the plate movements we're going to see
the rock
cycle and then we're going to see the
soil formation
now each one of these in terms of
geological cycles or events we're going
to find are very dynamic
they're always in a point of changing
and take for example tectonic plates
we think back to what the planet was
like
uh going back to the time of pangaea
and how our continents drifted to the
continental drift and how it spread
parts of
our land masses across the globe
now this idea of continents moving and
tectonic plates
is also one of the ideas that still
happening today we know we're not going
to see that these
plates are moving at astronomically high
rates
but it's this plate movement that'll
give rise to things like earthquakes or
volcanic eruptions
which are again dynamic part of changing
the world around us
so first thing to look at here in terms
of interactions
does involve looking at this kind of
tectonic cycle
and we're going to see this involves
this level of convections
and hot spots now that liquid core we
have as we're going up and then into
the mantle this is very very
very hot and again hot kind of an
understatement here
but this level of heat or energy
that we have coming from the mantle and
the core
is going to create these plumes of the
hot magma
that will move upwards in the mantle
and as it moves upward in the mantle
it's going to create what we call these
hot spots
where that multi material is going to
reach into the lithosphere
so if you imagine for a moment here that
we've got this mantle
using these convection currents and
moving up
it's going to come through and work its
way into the lithosphere so a little hot
spot we can see being generated here
now this idea as we're looking at this
kind of tectonic plate movement
you can time the fact that as these
plates
as these layers of the lithosphere move
you're going to find that those plates
are always in constant motion
and that some are separating and that
some are colliding
now the actual theory here of plate
tectonics
is one that goes all the way back to
about the early 1900s
in terms of showing how the earth used
to be aligned
in fact one of our best sources of
evidence to support
this theory about plate tectonics
doesn't come to serve from the geology
but comes from the actual fossil record
and we're going to see that as we look
at different layers here of our fossils
there are certain types of rock
which are the sedimentary rocks that
support fossils
we can see comparisons that fossils
are the same in certain parts of
different continents
so here we can see that north and south
or south america and africa
have this region which compose the same
type of fossils
we could also see areas here up in
northern south america
and over here in this western part of
africa
which would have similar types of fossil
records
and these are just showing that areas at
one point in time used to be connected
and that as the plates have moved
they've caused the separation
across the planet
so when you account for all these
tectonic plates in terms of the cycle
you can see it's a very
dynamic system we have plates that are
spreading which we're seeing here as the
red
and we have plates we call the
subduction zone
and that subduction essentially if we go
back here just two slides
we can see that this is where one plate
slides below another one
and this might be a point where you
actually produce this
increase in a higher mountain range so
as one plate slides below the other one
here
it forces that crust a little bit higher
up and you've got this
increasing land mass we can also see
that
in these subduction zones as we are
sliding past these plates it creates
some of these spots again
we think about that little hot spot
where you can get that magma
rising up here into that lithosphere in
this case we can see the formation here
of a volcano caused by that subduction
zone
now that spreading zone also produces
this ability to
create this void but in this case now as
the magma comes up
and solidifies it creates this ability
to generate
this greater amount of the crust or the
greater amount of that lithosphere
we see here on the outer part of our
planet
so again we've got these areas here and
if you especially look
along the western coast of north america
you've got this spreading zone this week
concealed a lot of times
as the fault zones that allow us to
generate
a lot of the earthquake activity along
the western coast
we also though have areas which we call
the collision zones
as you can see here these little dotted
line type circles areas
we can see over here a nice little
collision zones
and we also find that in this
directional plate movement you find that
some plates here in terms of a caribbean
plate
are moving kind of the east to west
direction
where when you're looking at plates here
maybe along south america
it's going west to east so these plates
are always moving in different
directions
in this case this spreading here along
the mid-atlantic line
you've got spreading out towards the
caribbean
and you've got sorting out towards
europe in terms of those changes
but this movement again we're seeing in
tectonic plates is a
really big change in our environment and
even though it's a really slow
constant motion we see that we give new
lithosphere developed at that spreading
area
and we've got other lithosphere that's
now being essentially
brought back down the mantle but also
causing this rise in some of our
actual land mass the lies of our
continental crust
to where we're living today
now the idea of all this kind of plate
movement as a downfall
does bring up again those subduction
zones which produces
volcanoes so as that tectonic plate
moves over one of those hot spots
and we've got that magma rising up into
the lithosphere
we can now have the magma forming into
that volcanic activity
those volcanoes then are going to allow
us to see this release
of the molten lava essentially which is
that magma from the mantle
as well as amounts of ash and gases so a
lot of our
expelling sometimes the carbon dioxide
or other toxic gases coming out from
these areas
now we're looking here at the hawaiian
islands and if we go back and compare
the hawaiian islands in terms of where
they are on the actual planet
you're going to see that these are kind
of middle of the ocean
there really is not just one fault line
here
where you're seeing a subduction zone
but as this
pacific plate starts to move you're
going to see that that movement going in
this case from the east to west here
is what's causing this volcanic activity
it's allowing us to show
this uprising that it creates these
little hot spots and we can see here
all the several different little
volcanoes
that are being produced across the
hawaiian islands
now when you get these different
tectonic plate movements
you're going to find there are three
types of movements that we see
the first one we get is what's called
the divergent plate boundaries
essentially this is where you're going
to get that separation so when the two
plates separate
this is we're going to have the uprising
here of that
molten magma so moving up from the
mantle here
through the athenosphere into the
lithosphere and that's what's going to
create new crust and a lot of times
you're going to see it's creating crust
in the oceanic environment it's an
oceanic crust
if we've got the conversion plate
boundary so divergent means moving apart
convergent means coming together this is
where you're going to get those plates
colliding
and you're going to create these
subduction zones
in this case this is where you're going
to have them collide in such a way
that you can get land masses forced
upwards you can get the volcanic
activity formed
as those hot spots are going through and
created as the magma flows on in
but it creates a very dynamic area where
these two plate boundaries coming
together
the third type we're seeing is what's
called this transform fault boundaries
and this is where instead of the actual
plates moving together
they're going to slide past each other
and as these plates
slide past each other you're going to
find that the sliding back and forth
is what creates these fault lines and
this is essentially where you're going
to see a lot of this
kind of activity with earthquakes as you
get this
transform fault boundary being generated
so when you're looking at all of these
different movements where you've got the
divergent or convergent and you've got
that sliding
these are all part of our tectonic cycle
essentially all the process itself
that are used to make more of our crush
so when you've got
that separation there and you've got the
mammal coming up that's
building up more of that crust if you've
got crust that's breaking down as it
undergoes
this abduction going down back into the
amount to be recycled here
these are all parts we're going to see
that are dynamically changing
that world around us now again it's not
going to be this change you see
overnight
it's a very very slow cycle with this
tectonic movement
so again we talked about that sliding of
faults
this or the sliding of the plates this
is what's going to create that
fault zone and a fault essentially here
we're going to see is a fracture in the
rock
across where we've got that movement
an earthquake then is going to occur
when the rocks itself that we see as
part of this
lithosphere moving back and forth are
going to all suddenly rupture
and as they rupture
it's along this fault line
now we can see here that this kind of
cavity we've got
which is our san andreas fault
essentially is
this fault zone it's a fault zone here
we've got a lot of cyber activity we've
got a lot of these plates sliding back
and forth next to each other
and we've got what's called the
epicenter this is the exact
point right above where that rock is
rupturing below
so down here you've got as these plates
slide past each other
you've got this involvement with the
plates themselves the earthquake
develops way down low and then permeates
up here into our upper crust
and that's where you're going to feel
that greatest effect in terms of the
magnitude
of that land that's moving around us so
again you have the fault
which the fault itself is going to be
where the rock is going to fracture down
there
in the lithosphere the earthquake then
is where that rock itself and this
sphere has
ruptured along that fault line
your fault zone then is where you're
going to see that movement
in the actual crust and the epicenter
then is that central point
right above where that rock is
undergoing that rupture
now in terms of actually measuring this
level
of tectonic movement we have what's
called the richter scale
and the richter scale is like our ph
scale
it's logarithmic and that means as you
go from
a level of one to two or two to three
it's ten
times greater in force and so as you're
moving up in the scale
if you went from this case a earthquake
as a magnitude of seven
or you had an earthquake magnitude of
six there's a tenfold difference
if you had the same idea we had a
magnitude six earthquake but then went
to a magnitude intensity
of eight it's a hundredfold difference
if you had six going to nine
you'd have a thousandfold difference in
terms of intensity
so again just like our ph scale where
you had the increase or the decrease in
the acidity
ten-fold there we see that change here
also on the richter scale so it's not
just
one simple change but it's a ten-fold
change going from one level the next one
on that richter scale
now our second type of cycle we're going
to look at here is the
rock cycle and the rock cycle is
involved in part with
some volcanic activity especially when
it comes to
the kind of separation of the rock or
even the placement of the rock
but with the rock cycle we're going to
see this as a point
that again it's very dynamic and it's
always constant
it's constant the factor that it's
forming new rock and that rock is being
returned
back to its original form this is where
a lot of that subduction happens
that as the plates slide below each
other that lithosphere as it moves back
down into our mantle or
the upper portions of the athenosphere
it's going to go back into that liquid
magma or that more molten magma and it
moves away from being this solid form
which think about as the soil or the
earth beneath
our feet now there are three types of
rock
that we can see here we have the igneous
rock
which in this case here is a result of
the mantle itself moving further up
and cooling and crystallizing that's
going to produce things like the granite
that may make your countertops up if we
increase the length of time that the
igneous rock is there so we have an
increase in heat and pressure
we can change that into what is called
the metamorphic rock
so this is now your marble or your
quartzite making up the material
and at the same time if we have other
materials here
where that igneous rock is pushed to the
surface
and then it gets weathered so it gets
eroded away
that igneous rock can form as it gets
compressed again over time
into sedimentary rock this is things
like our limestone
now that sedimentary rock as well as
igneous rock could all
transform back into the metamorphic rock
which is again that marble type form and
that's all because of heat and pressure
over time
each three types of rock though can all
be returned back to this original kind
of form
as you undergo this subduction or even
the melting
that if we get magnet exposed to it we
can convert them back
into that liquid or molten form of the
magma below the earth's surface
so with igneous rock here this is what
you can see has directed involvement
from the magma
or the mulching material within the
mantle and we have two main types of
igneous rock
we have the intrusive igneous this is
where it's going to form within the
earth itself
as a magma rises and cools or we have
the extrusive igneous
and that's where you're going to find
that a volcano
has erupted that lava or ejects the
magma outward
so intrusive occurs within the crust
where the extrusive occurs
outside that crust now sedimentary rock
we're going to see
occurs in the forms here as the result
of that igneous rock
as it goes to the extrusive type of
production
it gets weathered and as that ignis rock
gets weathered we have the sedimentary
rock formations
this one can produce things like our
muds our different sands
even the gravels we think about as a
sediment that we see around us
now the sedimentary rock again is kind
of important in this scenario because
this is where you're going to see all of
our fossil formation
you will not see fossils forming in the
igneous rock you will not see
fossils forming in the metamorphic rock
but as we said earlier both the igneous
and the sedimentary rock
as they go through processes of
overall cycling they can all convert
back
into metamorphic rock which means that
this rock
is undergoing high extremes of
temperature and pressure so it's still
within our
our crust and as it undergoes those
changes
this can also go back into that molten
form of our magma
as it turns it back to a cycle now it's
kind of interesting because when you
think about the rocks around us you
never think about the fact that they are
in turn cycling from form to form
because we want to get to witness them
using one
potential now of course when we think
back to our
carbon cycle or the water cycle that's a
lot easier to see that transition
but the rock cycle this is again taking
place over billions of years
the point of flowing these different
types of rock in the world around us
so when you have that igneous rock
that's moved up as part of the extrusion
or pushed up
based on plate tectonics we're going to
find that weathering itself
has a major impact as we convert that
igneous rock
into these sedimentary structures
so the fact of weathering itself is not
say
a storm moving through but weathering is
where the rock itself that we have
exposed
is going to have the air eroding away at
it we're going to have water
working away at it even certain
chemicals or even structures like trees
can go through and break this rock down
so physical weathering is the effect
here that we're going to have the rock
broken down over time
due to some interaction from the world
around us
so you might have physical weathering
being a tree growing through and the
trees are
pulling the rocks apart due to small
little pressure
you might have a wind-driven
rain that arose certain sides of a
rockaway and create certain formations
these are all physical weather in itself
that over time
is going to cause these formations to be
shaped in certain ways
chemical weathering though is where the
rocks themselves
are breaking down as well as the
minerals by a chemical reaction
so that same water that we might see as
eroding rocks away on a beach line
or smooth them down the river you're
going to find could also be the effect
of chemical weathering
because now as water say trickles
through our soil
in this case moves into a cavern the
actual deposition
or the depositing of minerals can create
these rock formations
in this case you get the slag types and
slag mites
that some of these are going to be
dripping down and the sediment as it
drips creates a longer part up top
or as it drips the bottom surface it
creates a little taller one on the
bottom
but these scenarios again that dripping
water is also rearranging that rock it's
weathering the rock
in different formats so again physical
weathering
is some kind of mechanical structure
could be caused by water by
wind by life forms that cause these
cracks to develop where chemical
weathering is where the rocks themselves
were breaking down
as well as the minerals due to a
chemical interaction
so elements themselves were being
dissolved from that rock
and they're being released as part of
this change
so when you get to erosion then this
essentially is kind of like
the weathering but the erosion is this
physical removal that as we've wetted
away that rock
these rock fragments style can be moved
on that landscape
again a lot of this is a physical aspect
because of the wind-moving
sand or soil the water causing the flow
even ice itself can go through and
transport
materials think about say an example of
gold mining
and how gold deposits have been moved
across landscapes
and a lot of times think about how a
glacier might push
these soils or these rocks down a
stream or down a mountain it's going to
deposit these minerals in different
places
as part of this erosion effect you can
also find that living organisms
so humans can cause materials to erode
think about how we interact with our
beaches we get the beets erosion
due to our influence of inlets or
different rock breaks and a lot of this
can have an effect on how
that physical environment is being
disturbed
now deposition is kind of the opposite
erosion is moving it away
but deposition is not what we're going
to accumulate or we're going to get this
eroded rock or material to actually go
through
and build up now with the deposition as
part of this process
you're going to see that this is one
factor
that we kind of include
in the weathering here because it helps
to build materials up
and so even though you might find that
erosion itself is moving materials away
with the erosion you also have to have
deposition and so one place kind of
think about this
is material moving down the mountainside
we can go back to gold if you want
as streams go through and erode away
rock deposits and they let the rock
expose that gold and it moves into the
stream system
that gold moves down that waterway
and it moves the point where it's
deposited in little pockets here and
there
you could also look at the louisiana
delta that as the soils and sediments
move down the mississippi river
you get them deposited there at the very
end as they make their way
into the ocean so erosion and deposition
kind of go together here
and the fact that one is moving it away
where the other one accumulates that and
hopes to build back up these areas
as part of a rock cycle
now when we look at the plate tectonics
there as part of this feature
and combine it with a rock cycle we find
that this brings us then
into our soil cycle and how the soil
cycle itself
is going to link all this back into our
biosphere
now soil is a little bit different
because when you look at something like
our rock
the rock is that key element that we
have it as either the igneous rock the
sedimentary rock
or we have the metamorphic rock
but soil is a result of that weathering
it's a result
of the erosion and of that deposition
and that's because the soil itself is
vital for
our planet to survive we have it as
a medium for our plants to grow in if we
think about the permeation of water
through the soil
we have a filter to bring out
contaminants
we can have it as a habitat think about
a gopher tortoise living in
the soil with a brill we also find that
it's important for our filter for other
pollutants
think about maybe something like a
wetland as those
polluted waters move through that area
it can
filter out those heavy uh metals or the
other sediments there and deposit them
in little pockets
that over time can be broken down and
returned back to different forms
but with the soil itself you're going to
find it's kind of this
very diverse structure that provides
all these different types of ecosystem
services so
think about the soil around us you know
we can't take it for granted but we have
again as a filter
we can filter our drinking water we can
have it as a habitat so you have an
earthworm
or a little microbes our nitrifying
bacteria can live there
we have it as a place for plants to go
through and grow
so the plants themselves will use up the
nutrients here but as the plants die
back those nutrients are recycled back
into that soil so we can find that this
kind of ecosystem surfaces
all come from this soil itself but that
soil again goes back and corresponds to
our rock cycle with the weathering the
erosion and
the deposition
so in terms for soil to actually come
into existence we have
five factors that contribute to what
kind of soil
and kind of the
uh that the
the properties of the soil that we
encounter the first thing is where it
comes from and that's our parental
material
so what is our soil made from and how
has that been influenced
so when you think about getting back to
our rock structures there
if we've got this soil coming from
quartz
or maybe we have it coming from
something more like limestone
this is all going to change the
different properties of that soil
as it comes into our habitat or to our
environments
you're also going to find that the
climate is going to influence that soil
as well
in the case for climate you're going to
see that colder climates or warmer
climates can influence
different types of soils so if you've
got a soil in a high
latitude in the northern hemisphere or
maybe in the southern hemisphere high
latitude
you're going to find a lot more organic
material and that organic material here
does not decompose as quickly due to
that colder temperature
if you move to our equatorial range
though
you're going to find a lot more fertile
soil because now that warmer climate
allows for a greater level of
decomposition and a lot of the organic
material can go through and be utilized
as this nutrient-rich area you also find
that the topography
the area we find in terms of the actual
high points and low points uh can
actually influence that soil as well
if you've got soil that forms on a
mountain slide so a very steep sided
slope you're going to find that erosion
or that weathering
has a constant factor on moving that
soil around
if you've got that soil that forming say
in the valley
that valley is going to accumulate gonna
have a lot more deposition and it could
change that consistency
even the life forms that we have as part
of that soil are going to influence what
it can and can't do
can you think about an organism like a
plant or an animal that moves through
that environment
plants might use up the nutrients but
same time return nutrients back to that
soil
as they die away animals might go
through and move through a soil
helping to mix soils up maybe add
aeration will add water flow
and supply that what a better source to
supply those plants in turn
with ability resources the last one to
get here in terms of formation
is just time if the soil has a long
time to sit there and develop you're
going to find that's going to change its
properties
if you've got young soil versus say very
mature soil
you might find over time that soil might
be rich with nutrients
or might be depleted it all depends on
what vegetation
and what our life forms have been there
so a new soil you might find
doesn't have much in terms of organic
structures because not a lot of
decomposed
but same thing with mature soil it might
have some level of organic material
but also might have some depletion due
to the fact that the organisms around it
have used it up throughout time
so again with our formation of soil all
of those factors we talked about the
climate the topography
the life forms the time and even the
parental material
will all play into how this soil is
formed
so in this case we can see our parental
rock here uh we're going to have it
weathered and eroded over time
and that those fragments as they were
eroded and weathered are going to move
upwards into this top layer to create
that soil
our little bit more older soil we might
call the young soil here
you're now going to find that organic
material starts to build up over time
and that's all because the plants
themselves are starting to create these
voids for
water to permeate the same time that as
they use up some of the nutrients
those plants are dying back down and
supplying more nutrients through those
soils
as you get into more mature soil here
you're going to find that the greater
amounts of organic matter start to
accumulate
but at the same time you might find some
depletion of certain
elements depending on how old or how
mature that soil is
now this time formation for this soil
will actually also take us back to
we talked about what's called primary
succession because primary succession
is part of this process if you break
things
back down just to bare soil and let's
say
volcanic activity goes through and
deposits
all of that extrusive igneous rock so
all the magnet solidified
that rock has to go through this
weathering over time
to fragment it and that allows then
smaller growth and eventually larger
growth to overtake that
as the rock itself or the soil starts to
accumulate
in greater and greater quantities
now when we're looking at soil we also
have what are called soil horizons
and soil horizons are working on develop
in the skecher as a layer essentially
that are going to be very specific as to
what that layer can contribute
so the very top layer we get is our
o horizon and the o horizon we think
about as just the organic material
this is where you've got a lot of life
forms of course our grasses
and other plants and these are we're
going to have
some type of growth as well as some type
of decay
so this is where your leaf litter is
accumulating uh dead
animals might be or animals not
defecating or animals might be dying on
the surface here
this is really rich with the organic
matter
now below that o horizon we go into the
a horizon
this is our top soil so this is the area
we're going to find
that has organic material it's also
mixing with some of our mineral content
so you might have a greater level of
some of the rocks that were there before
being weather accumulated in that region
as you're getting down into this top
soil area
you will find that the organic material
here
is a point at which we don't see as rich
as a top layer
now below this top soil we get into the
b horizon which is the
subsoil this is where you're going to
find this case a much greater
deposition or accumulation of a lot of
times things like our metals or heavy
metals
and even some nutrients now that b
horizon itself
you're going to find here that this is
where
if we've got nutrients wanted to be
accumulated by
the plants this is where the roots try
to come down to gather some of those
nutrients
now the sea horizon is also considered
the subsoil here
but this is the one that's furthest away
from the weathering so furthest away
from the influence of wind
or time or even just the water
and this is where you're going to find
the cereal or horizon itself here is
most similar
to what we started out with for that
soil
now this layering we're showing here
so 0.1 meter 0.3 meters 1 meter 1.3
meters
this is by no means set in terms of
where you find this
but this is kind of just the average
layering effect we get
that the topsoil here is your really
your organic and rich area
this is what's going to actually be say
supplemented with if you add in
fertilizers and you add in your
say manure or compost your
nutrients then we'll try to travel down
into that a horizon and b
horizon and that as you have kind of
these slow releases this is what we want
to permeate down in
essentially we want to leach down into
these soils to help feed these plants
over the long term
this is also one of the things when you
think about say water in your grass
as an example here if you are watering
all the time
that water stays right up here in this
top layer this first little organic
layer
and a little bit into the top soil and
those roots won't be very developed
if you water intermittently though and
you water say
only twice a week or only once a week it
does create this drying effect in these
top soils
which will cause your plants or
vegetation to create these little bit
longer reaching
roots and those roots now come down into
these subsoils
where that water supply is sometimes
more consistent
that allow them to have this chance to
bring water in even during times of
drought for those conditions
so again the o horizon is your organic
layer that's the one we see as
the plants that are living and dying
essentially a horizon is your very top
layer
of your topsoil this is where you have
again organic material but you also have
to get the minerals mixed in
you have your b and c horizon with your
subsoils
the b horizon has mostly mineral content
with a little bit organic material
where your c horizon is pretty much all
of the unweathered or the least weather
material
which is most similar to that parental
form that started the soil production
now in terms of the properties of soil
you're going to find there are three
parts that make up soil itself
we've got clay we have silt and we have
sand now this property
you're going to find creates the texture
of the soil that we are experiencing
and the quantities itself you find in
that soil
will all depend on the percentages of
each one of these
now when you're looking at probably the
most
we could say abundant form or the form
that maybe
is uh the middle
in terms of all these distributions we
have what's called loam
and loam is approximately 40 sand
so a good quantity of sand here about 40
percent
silt and only about 20 percent
clay now this kind of formation with the
loam
you're going to find is going to be
having this ability to go through
and permeate water in certain ways
in fact a lot of the soil's ability to
allow water to percolate
to filter or life to grow will depend on
the percentages here
that we get from the clay the silt and
that sand
as they come together so we can see here
right in the middle this loam
is kind of that middle where all the
sand the silt and that clay
come into this kind of middle percentage
here if we're looking at a sandy clay
or see a silky clay we can see each one
of these are going to vary
in those percentages if it's all sand or
all silt
or all clay even that will play into the
properties
of that soil itself again the
proportions you get of each one of these
different types of materials that silt
that clay in that sand
are all going to determine your texture
of the soil as well of how that's going
to influence
the interactions with the soil and life
around
it so that texture
then brings us to what's called porosity
and porosity essentially allows you to
see
how well water drains or how
poorly water drains through that
material
so when you're thinking about this
initial form here
when you've got the sand the silt or the
clay you've got water going through
your sand is the most permeable it's
got the greatest porosity that sand acts
as a really really good
filter the water itself can permeate
through
filter out some large materials at the
top and then even smaller ones as it
moves further and further down with that
poor size
if you're looking at silt though silt is
a structure you're going to find
as part of a deposition so when you're
looking at
a river depositing soil or material
along the banks that's a lot of time the
silt it's
decay matter uh a little bit smaller
actual size of the particle in fact when
you go back to our little
image over here you can see that sand is
.05 millimeters to two millimeters
where that silt is even smaller point
zero zero two to point
zero five millimeters now when you're
getting into
a clay version you're going to find
that's even less porous
and this is why a lot of times you live
in an area that has clay soils water
tends to accumulate
it does not drain very well so in
florida which have very sandy soils due
to our
geological history water drains pretty
well
when you mix in say so the silt from
maybe the deposition of a riverbed
a little bit longer time to filter out
you have really
heavy clay soils though even harder for
that to deposit or to
allow the water drain through which
creates this kind of ability to hold
that water up
and keep from filtering that environment
but water can move through each one of
these is just the length of time you can
see here
one hour versus 100 days versus 100
years for that water to move through
these different type
of soils
now we also can look at one other factor
here and it's one that you probably
haven't heard of
and this is considering the kind of
chemical property
of our soils and as we examine
this kind of chemical property of our
soils we're going to look at what is
called the cec
or the cation exchange capacity
and essentially this is the ability of
that soil type and mixture of the salt
the silt the sand and the clay to absorb
and release the cations remember cations
here we think back to some of our
chemical interactions
these are positive charged ions in this
case not just any ion but
a mineral type ion in this cation
exchange capacity you're going to see
that this
is the ability then for that soil
to hold on to the certain nutrients that
we find in that area
now if we're looking at this cec as a
measurement here
you're going to find that soils with a
really high level of cec
can go to provide a really essential
ability for the cations
to pass to the plants in this case here
we can see this is a really desirable
area
for growing crops now if we find that
there is a change here
in our soil content looking at say the
clay content
you're going to find now that as a
higher level of clay is
present there's more water accumulation
and now that water accumulation means
this crops can't grow
so this cation exchange capacity as well
as porosity
are going to play into factors to
determine whether or not this soil
is good for agriculture or not so again
clay is one of these things here
may not seem like a really high
contributor to the soil but the clay
itself as it accumulates it can be good
to attract some of these positive
charged
ions but at the same time if you get too
much you can have little water
permeation
which is going to cause plants to not
become waterlogged not be able to grow
in those areas now when you think about
this kind of chemical property it also
involves
the relationship between we call the
soil bases
and the soil acids so elements or
minerals here like calcium or potassium
and sodium
these are our soil bases which interact
with soil acids like
aluminum and hydrogen
and what we want to see here with these
interactions from the soil bases and
soil acids
is the fact we look at what's called the
base saturation
the proportion that we get between these
two and
measuring how that soil
itself is going to perform now
the actual efficiency here for the soils
in terms of nutrient availability
does play a lot in terms of the cation
exchange capacity
plays a lot in terms of that base
saturation to determine how productive
that soil can be if that soil itself has
a really good
base saturation or high level there
you're going to find that the clay
especially as a really good cation
attractor can hold along these nutrients
and so things like our magnesium or
potassium
can be held on in that soil if you have
soils that are not really good at
holding clay or having clay like a sandy
soil
you're going to find that nutrients to
get depleted very quickly
so a very waterlogged environment that
maybe has very sandy soils you might
find
it's not perfect for all plant growth
but only certain types of plants that
can find nutrients in other ways can
survive in those conditions
now we also find the fact that as part
of the soil beyond the chemical beyond
the weathering beyond just the actual
properties of what is there that life
forms play a part
in what soil can and can't do and that's
because the life around us in terms of
small little microbes like bacteria or
protists our fungi even larger ones like
maybe an earthworm or even a mole are
all going to play
a role in reorganizing that soil
and we think back to our cycle with
nitrogen for example
we can find bacteria are particularly
important
and changing the atmospheric nitrogen
into forms that are usable by plants
you might find that the destruction of a
mole even though it creates a cavity
down there might push soil up
helps to move soil around helps to
create voids for water to flow or
roots to go through and find accumulated
nutrients
these organisms that we find in and
around the soil
help to kind of farm that soil and to
create the nutrient though that is
essential for
plant growth or even the agricultural
growth to keep that soil
in good health for us
now if we're moving away from the soil
we can move
into then some of the other minerals
that we find as part of our environment
and when you're looking at kind of the
composition of the elements for the
earth crust
you're going to find that a major
portion here is oxygen
followed by silicon followed by aluminum
and then quantities of iron magnesium
calcium and then a whole other set
of elements this kind of unequal
distribution of minerals
is one of these factors here that we're
going to see contributing
to why certain environments is
part of a good mining area or a poor
mining area
but when you look at the geological
processes you're going to find that
these
materials which you might consider as
the ores or
these metals are going to make up
different ways the environment is going
to go through
and retain structures now the reserves
we think about in terms of these finite
quantities we've always talked about the
resources that are available to us
reserves themselves here we know have a
certain quantity that we can go through
and actually recover
so when you think about mining
operations that are going through and
utilizing
different depositions of wars or
metals in our environment you're going
to find that these
are the elements or the minerals we
could say that are most useful
so we think back to our very beginning
idea in this chapter talking about the
transition from
say fossil fuels over to say
hybrid technology we have to think about
some of these
metals or some of these
low reserve materials that we're trying
to mine
now you can see here that in terms of
reserves the iron itself has a pretty
large
global reserve we've got 120 years
remaining
technically that we can mine in terms of
united states that we only have about 40
years remaining for our resources
you're looking at aluminum us only has
two years remaining that we can mine
on our own turf globally we have about
330.
now when you're looking at all these
approximations for these
metal reserves keep in mind that as
these elements
in terms of their ability to you know
conduct electricity are used in other
technological fashions these may not be
always accessible you may have to clear
coat of force to get to these materials
or you may have to destroy mountain
ranges to get access to these structures
so these actual accumulations of these
materials when you're looking at
something like the iron or the aluminum
or the gold
that metal itself as a value is actually
concentrated within the
or structure and we define or is we're
going to find that or itself
is this accumulation of minerals which
we can find
some type of valuable material to
extract from
so maybe an iron ore or you find ore
where the copper is found in where we
say silver for
an idea there in these different
elemental buildups or these different
materials that are building up
you're going to find that the ore itself
sometimes it's hard to recover
depending on where it's deposited
now the fact that the distribution of
these minerals
are not always equally spread out
through the planet and that they find in
certain
kind of hot spots throughout the globe
means that
the distribution of these can have
really big consequences not only on
environmental areas but also
social consequences of how we interact
and so one thing we have to think about
here especially with our involvement in
the world around us
is a mining operation if we want to get
access to these reserves of metals
to use an industry we have to mine them
out
and one of the more common types of
mining we find
is surface mining and this is where
we're going to remove those minerals
very close to the very
top earth surface so right there kind of
at the top of the crust
so whether it's the strip mining the
mountain top removal
the plaster monitor or the open pit
mining these involve kind of scraping
that top surface
so with strip mining we're going to see
that they go through and remove
that top soil when we go down to expose
that subsoil and that the subsoil there
is where we have some of these essential
metals deposited
one of the things you find with strip
binding though is that there's a lot of
waste
when you have to remove all that topsoil
whether it's one foot or
40 feet or even further that topsoil
and that waste we call tailings has to
go someplace
even once you run that material through
a mine and you pull out the elements or
the metals you need
you have all this waste material that
has to go back in about environment
now in the case of open fit mining this
is a little bit different because now
it's still on the surface but you're
digging down in and you're making a
larger
larger hole again you've got
waste to pull out from there but you're
digging down into that crust
but you are visible from the top in
terms of really big
say canyon when you're looking at the
mountain top removal this is where they
will go through and take
the entire top of a mountain away in
terms
of blasting it with explosives to then
be able to get out the ore
and the metals placed inside
one that maybe isn't as much of an
intrusive type of mining might be
plaster mining
because with this one you're not so much
going through and stripping away all the
soil
you're kind of pointing and searching
looking for small little accumulations
where the metals have built up
in say maybe a river now the only
problem with plaster mining comes the
idea is
that you can have really bad effects
that if you're using water to say a road
a side of a bank you're moving material
at a much higher rate than be naturally
taking place
now again all these types of mining here
you know we're trying to get to those
reserves of the metals trying to go
through and find those ore deposits
but again we're going from the top down
if we look at what are called subsurface
mining then this is where now we
actually bore
into the earth's surface we go down into
that crust
you know to the point of finding these
much deeper deposits
and for this idea you're going to see
that the subsurface mining
is not going to have so much effect on
the upper surface
but you are going through and having to
use
electricity to get down in there if you
use fossil fuels you have to bring
equipment
you also have to go through and control
your contamination potentially of
water supplies depending on where you're
mining it
so in terms of these two types of mining
properties the surface versus subsurface
you're going to find that yes we can get
to these ore supplies
but it may not always be for the benefit
in fact when you look at the effects
here in terms of
air you see that surface mining you're
moving a lot of soil
that can create dust clouds move through
to move
lots of dust across the area subsurface
once you're not having that much of an
emission in terms of the
actual dust but with your ability to dig
down in
the fossil fuels and their emissions of
co2 could have effect on the air quality
water quality you're going to find in
both scenarios some type of
contamination especially depending on
what type of mining you're doing
with surface mining you've got a lot of
runoff you've got
the washing of the materials uh where
you've got
the washing what they call the tailings
trying to let the
metal be remained you have to then have
those tailings
accumulate someplace and you know if
you've got a leaky machine with oil
you've got contamination there
in some cases with the subsurface mining
again we could have the effect
on maybe a water reserve but if we have
an acid mine
you could find those acids that they're
using to mine through that area
could also leak into that water supply
as well
and of course on soil you know on the
subsurface one
you're not affecting the soil you're
going down in one little spot having no
effect
but on most surface mining operations
that soil is drastically altered
where you move it away you replace it
and even though you might reclaim that
soil
it has to go back through all those
levels of building back up the organic
material
back to the point of a really good
habitat
so you can see that mine itself is great
to get access to these reserves we know
we're there
but it all comes down to a price is it
worth it to actually get
access to these materials do we need
them can we recycle it from someplace
else in terms of
making it sustainable for us to live in
that environment for it
so again these mining types here surface
money using more damage to our
environment
subsurface not as much but it's a much
dangerous more dangerous type activity
because now you're below ground
air quality can change very quickly your
confined areas you can have explosions
or collapses
so they all come with a cost in terms of
that mining
all right so that concludes our chapter
six which was looking at kind of the
geological cycles here
uh chapter seven then we'll take it one
step further and as we talked about with
soils there
and kind of the health of that soil
we'll move into
our land resources and the agriculture
seeing how the different types of soils
might
supplement or support those in different
ways
