Download Class Notes: S6E5 g. Describe how fossils show evidence of the

Name:_____________________________________
Class:___Earth Science_______
Period/Block:________________________________
Date:______________________________________
Class Notes: S6E5
g. Describe how fossils show evidence of the changing surface and climate of the Earth
h: Describe soil as consisting of weathered rocks and decomposed organic material.
What is a fossil? What do fossils tell us?
What are the conditions needed for fossil
formation?
How are fossils found?
What are the main types of fossils?
•
A fossil is the preserved remains of a onceliving organism.
• Fossils tells us a great deal about plants and
animals in the past.
• They also provide evidence about how
Earth’s surface has changed over time.
• Fossils help scientists understand what past
environments may have been like.
• Tells us about the age of rocks.
• Quickly covered or buried by sediments
• Has to be protected from scavengers or
forces that cause destruction
• Most fossils found are the hard part of once
living organisms because it takes longer to
decompose.
• The activity of humans. Ex. Digging
Earth’s processes exposes them on the surface.
• Weathering
• Erosion
• Tectonic forces causes them to be uplifted
• Petrified/permineralized remains: Forms
when minerals from water seep into
holes/cracks of bone. When water
evaporates, only hardened minerals are left.
• Casts and molds: A mold (impression)
forms when hard parts of an organism are
buried in soft sediment, such as mud, sand,
silt, or clay. A cast forms when hard part
(shell) is dissolved and a copy is made
from hardened minerals that fill the once
empty space.
• Carbon Films: An animal dies and get
buried, heat and pressure squeezes out
gases and liquid from the body. What is
left is the element carbon. It looks like
silhouette of the original organism.
• Trace fossils: Forms when an animal steps
in soft sediment (mud or silt) making a
footprint and becomes buried in layers. The
sediment eventually becomes rock.
Paleontologists use these clues to
determine size, weight, and how they lived.
• Original remains: Occurs when most or
all of an animal/plant is trapped in tar,
amber or ice. This preserves the animal or
plant from decaying.
What is the law of superposition?
What is soil? How is it made?
How are soils classified?
What is soil composed of?
Soil Profile
•
Using relative dating, determining age of
rocks based on the location of fossils, the
law of superposition says that rocks are
deposited layer upon layer. Oldest are laid
first.
• Soil is a _________ of weathered rock,
decayed organic matter, mineral fragments,
_______, and air.
1. ________ breaks down rocks or minerals
on our surface, it creates a layer of rock
sediments.
2. Over time, the sediments break down even
more creating very fine (small) particles.
3. _______ and _________ add organic
matter, wastes and dead plant material, to
the rock fragments.
•
•
Soils are classified by their size
List particle by size from largest to
smallest
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Soil is made of rock and mineral
fragments, organic matter, air and water.
Ex. lawn clippings, leaves, stems, branches,
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moss, algae, any animal parts, manure,
sawdust, insects, earthworms and microbes
The decayed organic matter turns into a
dark-colored material called humus.
Humus serves as a source of nutrients for
plants.
The layers of different soil are called
_______.
On the top of A Horizon are leaves, twigs
and other organic matter called ________.
Horizon A is also called ____________.
__ Horizon has the darkest soil because of
the decayed organic matter.
B Horizon has soil that is lighter in color
because less _______ matter.(less fertile)
B Horizon gets minerals from A horizon by
the process of _________.
C Horizon is the lightest and _______ soil
layer.
The C Horizon contains partially
weathered _____ and very little organic
matter.
5 factors that affect soil formation
What is found beneath the horizons?
__________: a layer of solid rock that
contributes/adds to soil; also called ______ rock.
1. _____________: Soils in deserts contain
little organic material and also are thinner
than soils in wetter climates. Areas that are
wetter produce more plants needed to add
organic matter for healthier soil.
2. Slope: Steep hills have poor soil as gravity
pulls soil that forms downhill.
3. _______________: Type of vegetation
affects soil formation. As it decays, it may
add different nutrients back into the soil.
Little vegetation=less fertile soil.
4. Types of rock: Rock type affects the type
of vegetation that grows in a region. As
different rocks provide different
types/amounts of nutrients the soil may
vary.
5. Time: The longer a soil has been forming,
the thicker it becomes.