Location of Pennsylvania
P s
L E S S O N 1
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Chapter 1
How Land Features &
WaterformsWere Formed
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3
Key Questions
1. What are threeways
Pennsylvania’s land has
changed over millions of years?
2. How have natural forces
changed our land features and
waterforms?
3. Which of the natural forces
built up the land features?
4. Which of the natural forces
haveworn away the land
features?
KeyWords
natural forces
folding
faulting
highlands
glacier
moraine
erosion
weathering
Key Places
AppalachianMountains
Allegheny Plateau
Mt. Davis
AlleghenyMountains
Laurel Highlands
Pine Creek Gorge
Great Lakes
PoconoMountains
HowNatural Forces
Changed the Land
I
n the earlier lessons, you have learned
about the many physical features of
Pennsylvania. Some of these physical
features are the mountains, hills, plateaus,
rivers, and lakes. However, our state did
not always look the way it does today.
Nature slowly created these features over
many millions of years. In fact, humans
were not here to create physical features.
Let us look at how nature, or
natural
forces
, changed the physical features of
Pennsylvania.
Scientists believe that many millions of
years ago, most of the land we know as
Pennsylvaniawas part of ahuge inland sea.
Slowly, the sea dried up. Then, later, it
formed again. Thishappened several times.
Each time, large swamps were created.
Many animals lived in these swamps.
Many tall plants, some as high as one
hundred feet, grew in these swamps.
Every time the sea came back, the plants
and animals died. Great weight and
pressure from the seawereplacedupon the
deadplants and animals. Throughmillions
of years, the pressure and weight caused
these dead plants and animals to become
oil, coal, or natural gas. Oil, coal, and
natural gas are called fossil fuels. These
