Download Lesson 2- Physical Features

Lesson 2- Physical Features
Pennsylvania can be described by its physical features. Features are
the make-up or appearance of something or someplace. There are many
geographical terms that are used to describe our state such as mountains,
valleys, plains, plateaus, waterfalls, and many others.
In the southeastern and northwestern parts of the state, there are
plains. Plains are low, flat, level land. They are in the areas near Lake Erie
and on the other side of the state along the Delaware River near
Philadelphia.
Some areas of our state are covered with rolling hills and mountain
ridges. A mountain ridge is a long stretch of land that rises steeply above the
surrounding area. These mountains are part of a larger chain known as the
Appalachian Mountains.
Between these mountains are valleys. A valley is the somewhat flat,
low land between mountains. There are valleys of many different sizes and
shapes in Pennsylvania. Our school is located in a valley near the base of
Montage Mountain.
Much of our state is covered by a huge plateau. A plateau is land that
is higher than the surrounding area. The top of Pennsylvania’s plateau is flat
in some areas and rugged in other areas. Because this plateau is so large,
many other landforms are located on top of it such as mountains, hills, and
waterfalls.
Pennsylvania also has many waterforms. We have three major river
systems, which are streams, creeks, and smaller rivers that empty into a
larger river. These waterforms help to make up our lotic system, or moving
water system. We also have many ponds, lakes, and reservoirs. The still
waters make up Pennsylvania’s lentic system, or still water system.
This is a map of Pennsylvania’s River Systems.
Pennsylvania’s lotic system, especially its rivers, has made it very
successful. Pennsylvanians settled around the rivers because water is such an
important natural resource. Towns, cities, and industries developed close to
the rivers. Rivers also allow for the easy transportation of goods by ship.
Philadelphia and Pittsburgh are two cities that developed close to rivers.
Locate them on your map.
Lesson 3- How Pennsylvania’s Features Formed
As you learned, Pennsylvania has many physical features such as
mountains, valleys, and plateaus. Our state did not always look this way.
Nature created these land formations over millions of years.
Scientists believe that millions of years ago Pennsylvania was covered
by a huge sea. Over a long period of time, this sea would slowly dry up and
form again. As it dried up, swamps would form where many animals and
plants lived. When the sea filled up again, these plants and animals would
die and their remains would fall to the bottom of the sea. Over millions of
years the pressure of the sea forced these remains to form into fossil fuels,
coal, oil, and natural gas. This is how Pennsylvania got its many coal mines.
Once the sea dried up, the land began to form other features. The
mountains of Pennsylvania, including the Appalachian Mountains, are
believed to have been formed by a
process called folding. Deep
beneath earth’s surface rocks and
soil slowly pushed against each
other to force up some of the earth.
Plateaus can also be formed by
folding. Pennsylvania’s Allegheny
Plateau was formed in this manner.
This is an example of a folded landform.
Another way that landform features are created is through a process
called faulting. Faulting happens in an area where earth’s crust has a crack
or break known as a fault. Faulting occurs when the land in this area moves
and one part slowly rises on top of the other. The other part sinks to a lower
elevation. The land in the area of Gettysburg, between the Piedmont and
Ridge and Valley regions, was formed in this way.
About a million years ago, earth experienced an Ice Age, or a period
in which the climate grew colder so that snow and ice did not melt in many
areas. During this time glaciers, or huge masses of ice, slowly began to
move south from the North Pole. Some of these huge glaciers reached south
into the Allegheny Plateau. They also covered the northern parts of
Pennsylvania. As they moved, the heavy glaciers wore away or moved our
physical features. They carved thin areas for rivers and made some valleys
wider and deeper. In other areas, the land they moved created mountains.
The Pocono Mountains were formed by glaciers.
The Pocono Mountains were formed by glaciers.
When the climate warmed up, the glaciers began to melt. Over
thousands of years, the melting glaciers began to fill up the huge holes they
had left behind with water. Lake Erie and the other Great Lakes were formed
by glaciers. The water that ran from the glaciers also formed many creeks,
streams, and rivers.
Pennsylvania’s landscape is still changing to this day due to erosion.
Erosion is the wearing away of soil and land. The most common causes of
erosion are wind and water. Streams and rivers pick up small amounts of
rocks and soil. The soil and rock grinds up more soil and rock from the
waterforms. The forces of the running water and the grinding of soil and
rock have carved out rivers and deep valleys in Pennsylvania. Pennsylvania
will continue to change because of these forces.