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GEOLOGY AND CIVIL ENGINEERING
CEG 04
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I I Engineers, Geologists, & Society
A Engineers
1. Solve problems
2. Quantitative analysis emphasized
3. Models often simplified/simplistic
B Geologists
1. Study problems
2. Qualitative analysis emphasized (traditionally)
3. See earth as complex (heterogeneous & anisotropic)
C Society
1. Pays the bills for problems and regulates response
2. Confused by conflicting analyses
3. Sees geologists and engineers as mysterious
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The Geological Environment
Earth is an active planet in a constant state of change
Geological processes continually modify the earths
surface, destroy old rocks, create new rocks and adds to
the complexity of ground condition
Cycle of geology encompasses all the major processes
which must be cyclic, or they would grind to an inevitable
halt
Earth movemens are vital to the cycle, its hot interior of
the earth is the ultimate energy source which drives all
geological processes
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Cycle of Geology
Sea
Mainly deposition,
Forming new sediments
Underground
New rocks are
created
and deformed
Land
Mainly erosion
and weathering
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weathering
Land
Earth Movements
Igneous Rocks
Magma
Melting
Metamophic Rock
Metamophism
sedimentary Rocks
Liquefaction
Deposition
ErosionTransport
Sea
Air
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Discover How Rocks Are Formed
Sedimentary Rock, Metamorphic Rock
And Igneous Rock
http://www.fi.edu/fellows/fellow1/oct98/create/sediment.htmhttp://www.fi.edu/fellows/fellow1/oct98/create/metamorph.htmhttp://www.fi.edu/fellows/fellow1/oct98/create/igneous.htmhttp://www.fi.edu/fellows/fellow1/oct98/create/igneous.htmhttp://www.fi.edu/fellows/fellow1/oct98/create/igneous.htmhttp://www.fi.edu/fellows/fellow1/oct98/create/igneous.htmhttp://www.fi.edu/fellows/fellow1/oct98/create/metamorph.htmhttp://www.fi.edu/fellows/fellow1/oct98/create/sediment.htm7/28/2019 How Sedimentary Rock is Formed
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For examples of sedimentary rocks, take a look at these:
How Sedimentary Rock Is Formed
For thousands, even millions of years,little pieces of our earth have been
eroded--broken down and worn awayby wind and water.
These little bits of our earth are washeddownstream where they settle to thebottom of the rivers, lakes, and oceans.
Layer after layer of eroded earth isdeposited on top of each.
These layers are pressed down more andmore through time, until the bottomlayers slowly turn into rock.
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Sediment Transport
Gravity
Wind
Volcanoes Ice
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Sediment Deposition
Water
Sea
Slopes Volcanoes
ice
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Sedimentary materials
Sandstones Mineral grains
Physically and chemically stable minerals e.g quartz,
muscovite
Rock fragments and volcanic debris Clays
Breakdown products (clay minerals) and organic debris (plant
material to form peat and coal)
Limestones (solutes debris) Calcite precipitated from sea water due to biological activity
Gypsum and salt and other less soluble organic compounds
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Lithification
Definition This is a process by which a weak loose sediment is turned
into a stronger sedimentary rock.
Lithification process
Is induced by burial pressure and slightly increasedtemperature beneath overlaying sediments
Lithification Processes Cementation
Re-crystallization
Compaction Consolidation Normally consolidated
over - consolidated
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Sedimentary Rock Classification
Sedimentary Rocks
Clastic Rocks Non Clastic Rocks
Rudaceous
Coarse grained rocks
Arenaceous
medium grained rocks
Argillaceous
Fine grainedCarbonates Non-Carbonates
calcite
limestones
Allied rocks
ironstone
chert
coal
Salt and gypsum
conglomerate
Breccia
sandstone
Allied rocks
siltstone
Clay
Allied Rocks
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How Sedimentary Rock Is Formed
Sandstone Sandstone rocks are
sedimentary rocks
made from small
grains of the mineralsquartz and feldspar.
They often form in
layers as seen in this
picture. They areoften used as building
stones.
http://www.fi.edu/fellows/fellow1/oct98/expert/sandstone.htmhttp://www.fi.edu/fellows/fellow1/oct98/expert/sandstone.htm7/28/2019 How Sedimentary Rock is Formed
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How Sedimentary Rock Is Formed
Limestone Limestone rocks are
sedimentary rocks that
are made from the
mineral calcite which
came from the beds ofevaporated seas and
lakes and from sea
animal shells. This rock is
used in concrete and isan excellent building
stone for humid regions.
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How Sedimentary Rock Is Formed
Shale Shale rock is a type of
sedimentary rock
formed from clay that
is compacted togetherby pressure. They are
used to make bricks
and other material
that is fired in a kiln.
http://www.fi.edu/fellows/fellow1/oct98/expert/shale.htmhttp://www.fi.edu/fellows/fellow1/oct98/expert/shale.htm7/28/2019 How Sedimentary Rock is Formed
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How Sedimentary Rock Is Formed
Conglomerate Conglomerate rocks are
sedimentary rocks. They
are made up of large
sediments like sand and
pebbles. The sediment isso large that pressure
alone cannot hold the
rock together; it is also
cemented together withdissolved minerals.
http://www.fi.edu/fellows/fellow1/oct98/expert/conglomerate.htmhttp://www.fi.edu/fellows/fellow1/oct98/expert/conglomerate.htm7/28/2019 How Sedimentary Rock is Formed
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How Sedimentary Rock Is Formed
gypsum Gypsum rocks are
sedimentary rocks made
up of sulfate mineral and
formed as the result of
evaporating sea water inmassive prehistoric
basins. It is very soft and
is used to make Plaster of
Paris, casts, molds, andwallboards.
http://www.fi.edu/fellows/fellow1/oct98/expert/gypsum.htmhttp://www.fi.edu/fellows/fellow1/oct98/expert/gypsum.htm7/28/2019 How Sedimentary Rock is Formed
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For examples of metamorphic rocks, take a look at
these:
How Metamorphic Rock Is Formed
Metamorphic rocks are rocks that have"morphed" into another kind of rock.
These rocks were once igneous orsedimentary rocks.
How do sedimentary and igneous rockschange?
The rocks are under tons and tons ofpressure, which fosters heat build up,and this causes them to change.
If you exam metamorphic rock samplesclosely, you'll discover how flattened
some of the grains in the rock are.
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How Metamorphic Rock Is Formed
schist Schist rocks are
metamorphic. These
rocks can be formed from
basalt, an igneous rock;
shale, a sedimentaryrock; or slate, a
metamorphic rock.
Through tremendous heat
and pressure, these rockswere transformed into this
new kind of rock.
http://www.fi.edu/fellows/fellow1/oct98/expert/schist.htmhttp://www.fi.edu/fellows/fellow1/oct98/expert/schist.htm7/28/2019 How Sedimentary Rock is Formed
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How Metamorphic Rock Is Formed
Gneiss Gneiss rocks are metamorphic. Theserocks may have been granite,
which is an igneous rock, but heat
and pressure changed it.
You can see how the mineral grains in
the rock were flattened through
tremendous heat and pressure and
are arranged in alternating patterns
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For examples of igneous rocks, take a look at these:
How Igneous Rock Is Formed
Igneous rocks are called fire rocks and are formedeither underground or above ground.
Underground, they are formed when the meltedrock, called magma, deep within the earthbecomes trapped in small pockets.
As these pockets of magma cool slowlyunderground, the magma becomes igneous rocks.
Igneous rocks are also formed when volcanoeserupt, causing the magma to rise above the earth'ssurface.
When magma appears above the earth, it is calledlava. Igneous rocks are formed as the lava coolsabove ground.
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How Igneous Rock Is Formed
Granite Granite rocks are igneous
rocks which were formed
by slowly cooling pockets
of magma that were
trapped beneath theearth's surface. Granite is
used for long lasting
monuments and for trim
and decoration onbuildings.
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How Igneous Rock Is Formed
Scoria Scoria rocks are igneous rockswhich were formed whenlava cooled quickly aboveground.
You can see where littlepockets of air had been.Scoria is actually a kind ofglass and not a mixture ofminerals.
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How Igneous Rock Is Formed
Pumice Pumice rocks are igneous rockswhich were formed when lavacooled quickly above ground.
You can see where little pocketsof air had been. This rock is solight, that many pumice rocks
will actually float in water.Pumice is actually a kind of glass
and not a mixture of minerals.Because this rock is so light, itis used quite often as adecorative landscape stone.
Ground to a powder, it is used asan abrasive in polishcompounds and in Lavasoap.
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How Igneous Rock Is Formed
Obsidian Obsidian rocks areigneous rocks that formwhen lava cools quicklyabove ground.
Obsidian is actually glassand not a mixture ofminerals. The edges ofthis rock are very sharp.