Time and Change

1
Time and Change Rocks and Structures
The Earth is about 4.5 billion years old.
2
From http//earth.geol.ksu.edu/sgao/g100/plots/10
17_timeline.jpg
Humans have been here for a VERY small part of
Earths history. How do we know the rest?
3
Some changes take place very quickly!
From http//www.em.gov.bc.ca/Mining/Geolsurv/Surfi
cial/landslid/plate19.jpg http//www.nhoem.state.n
h.us/mitigation/Mt20St20Helens20wo20Frame.jpg
4
http//www.ferrara.com/columbia/attivita/viaggi/ar
izona/scorcio20grand20canyon.jpg
Some are much more gradual, but still dramatic!
5
Absolute Age The Actual time of an event in
Years Relative Age The Order that events took
place.
6
Families of Rocks
IgneousSedimentaryMetamorphic
Igneous Were at one time in a hot, liquid
state.
http//www.bishopmuseum.org/exhibits/pastExhibits/
1997/treasures/large_images/LOIHI2.jpeg
7
Magma is molten rock that is underground
Magma
http//www.solarviews.com/raw/earth/earthfg2.gif
8
Molten rock on the surface of the earth is called
lava.
http//www.southwestbirders.com/Hawaii_2002/lava2
0flow20i.jpg
http//mahi.ucsd.edu/Gabi/erth10.dir/lava-fountain
.jpeg
9
http//www.gsfc.nasa.gov/gsfc/earth/pictures/co2/v
olcanom.jpg
When lava is blown out of a volcano in small
particles it is called volcanic ash.
10
Rocks formed from lava or ash are called volcanic
rocks.
Basalt
Obsidian
http//images.google.ca/images?svnum10hlenlr
qobsidian
http//z.about.com/d/geology/1/0/R/K/basalt.jpg
11
http//www.gc.maricopa.edu/earthsci/imagearchive/f
loating_pumice_big.jpg
Pumice
12
Plutonic Rock From magma that has cooled and
crystallized beneath Earths surface.
Granite is plutonic
http//www.vermontmarbleandgranite.com/granite/img
granite/g4013rosaporrino.jpg
13
Solidifies as Plutonic Rock
http//www.uwsp.edu/geo/faculty/ritter/images/lith
osphere/Earth_Structure/igenous20landforms.jpg
14
When softer sedimentary rock is eroded, it will
sometimes leave the harder plutonic rock
formations.
15
http//comp.uark.edu/sboss/seds02.jpg
http//wrgis.wr.usgs.gov/docs/parks/mojave/oncolit
h255x212.jpg
Sedimentary rock usually consists of rock
fragments such as mud, sand or gravel that have
been cemented together.
16
Weathering the physical or chemical breakdown
of rock exposed to water, wind or ice. The
particles resulting from weathering -carried by
rivers to the sea floor-settle to form layers of
sediment-become sedimentary rock
17
If plant or animal remains are buried, they may
be preserved as fossils.
http//www.fox.uwc.edu/fossils/wisc/protax1.jpg
18
A Leaf Fossil
http//www.dll-fossils.com/Images/ginkgoalesleaf-w
eb.jpg
19
http//www.mineraltown.com/infocoleccionar/imatges
/rock_cycle.jpg
20
Metamorphic rocks were once igneous or
sedimentary. They have been changed by heat and
pressure under the ground.
21
Shale (sedimentary) becomes Slate (metamorphic)
22
Geological Structures
Fractures are cracks in a body of rock.-can be
formed by water freezing, earthquakes etc.
http//falcon.tamucc.edu/peichhubl/Pages/Clinkerm
acro.jpg
23
http//geophysics.tau.ac.il/personal/shmulik/image
s/fault20in20Arava.jpg
A fault is a fracture along which there has been
movement. Faults can be caused by earthquakes.
24
http//www2.nature.nps.gov/geology/usgsnps/klondik
e/mi8.2dikes240x247labeled.jpg
Dikes are igneous rocks formed in rock fractures
when magma is squeezed upward and later cools.
25
http//www.indiana.edu/geol116/week4/dike.jpg
http//www.geol.lsu.edu/henry/Geology3041/lectures
/04IgneousStructures/4-22.gif
A dike at Shiprock New Mexico
26
http//www.gpc.edu/janderso/images/folds.jpg
Folds occur when layers of sedimentary rock are
squeezed and then buckle.
27
Erosion Surfaces -when rock has been exposed to
weathering and erosion and later reburied,
the boundary is rough and uneven.
http//www.oldstoneage.com/montetwhite/kadarimages
/profile20photo.jpg
28
Strata means there are layers.
http//www.labyrinth.net.au/tdp/images/strata.jpg
29
Identify the structures in the diagrams on page
261 of the Text