8-2 Science

Chapter 2

Lesson 1

Topography

Topography:

The shape of the land

It may be flat, sloping, hilly or mountainous

Includes elevation, relief and landforms

Elevation:

The height above sea level of a point on Earth’s surface

Relief:

The difference in elevation between the highest and lowest parts of an area

Landform:

A topographical feature, such as a hill or valley.

Landforms may have different combinations of elevation and relief

Landforms

There are three main types of landforms:

1-Plains:

Made up of nearly flat or gently rolling land with low relief

Coastal plains are plains that lie along a seacoast

2-Mountains:

  • Have high elevation and high relief
  • Mountain ranges are groups of mountains that are closely related

in shape,structure and age

  • Mountain systems are made up of different mountain ranges in a specific region
  • Mountain Belts are long chains of mountain ranges and systems

3-Plateaus:

High elevation with a fairly level surface

Landform Region:

A large area of land where the topography is mainly made up of one type of landform

Lesson 2

How do maps and globes represent Earth’s surface?

  • Maps are flat models of all or part of Earth’s surface as seen from above
  • Globes are spherical representations of Earth’s surface
  • Maps and globes are made to scale
  • Scale is the ratio used on a model to the actual distance on Earth’s surface (I cm = 1000 km)
  • Symbols are used to stand for features on Earth’s surface
  • Keys or legends list all of the symbols used on a map

What reference lines are used to locate points on Earth?

The equator and the Prime Meridian are the two lines used to measure distance on Earth’s surface.

Lines of latitude and longitude are measured by degrees.

Each degree is 1/360 of a circle

Equator

  • An imaginary line halfway between the North and South Poles
  • It divides the Earth into the northern and southern hemispheres
  • Lines parallel to the equator are lines of latitude
  • Lines of latitude are also referred to as parallels
  • Lines of latitude are marked in degrees north or south of the equator

90° N

0°

90°S

Prime Meridian

  • An imaginary line that starts at the North Pole, runs through Greenwich, England and continues on to the South Pole
  • It divides the Earth into eastern and western hemispheres
  • Lines that run from the North to South Pole are lines of longitude
  • Lines of longitude are also referred to as meridians
  • Lines of longitude are marked in degrees east or west of the Prime Meridian

0°

Lesson 3

History of Mapmaking:

  • For centuries maps were drawn by hand
  • Explorers sketched coastlines as seen from their ships
  • Surveyors were able to make more accurate maps by determining distance

and elevation by using instruments and principles of geometry

  • Invention of airplane allowed maps to be drawn from aerial photographs
  • In the last 30 years computers have been used to create maps
  • Using digitized data
  • Using satellite images
  • Using GPS (Global Positioning Systems)

Satellite images are made up of thousands of tiny dots called pixels.

Each pixel contains info on the color and brightness of a small part of Earth’s surface.

Computers convert this digitized data into colors.

GPS is a method of finding the latitude, longitude, and elevation of points on Earth’s surface by using a network of satellites.

Lesson Four

Topographic Maps:

These maps show the shape of Earth’s surface.

Topographic maps are also known as contour maps.

In a contour map, each contour line is separated from the next contour line by a contour interval.

Contour Interval:

Difference in elevation between two adjacent contour lines.

Contour intervals do not measure distance between two lines on a map. To find

distance you would refer to the scale.

Common Symbols Found on a Topographic Contour Map:

  1. Index Contours-

Used to mark elevation on contour maps.

These darker lines may appear every fifth contour line or so.

  1. V –

These V marks appear where contour lines cross streams.

The point of the V always points upstream.

Water flows in the opposite direction.

  1. Slope (Gradient)-

Slope is gentle where contour interval is thicker.

Slope is steeper where contour intervals are very narrow.

  1. Closed Curve (Circle or oval)-

Used to mark the area with the highest elevation on a map.

  1. Hachure Marks on a Closed Curve-

These marks indicate a closed depression which might be an inactive volcano.

Another example of a contour map: