A HUMAN PERSPECTIVE One summers day at noon around 255 BC Eratosthenes drove a stake into the ground at the mouth of the Nile River in Alexandria Egypt Eratosthenes wrote down the angle of the shadow cast by the stake Around the same time in ID: 614570
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The geographers toolsSlide2
A HUMAN PERSPECTIVE: One summers day at noon, around 255 B.C., Eratosthenes drove a stake into the ground at the mouth of the Nile River in Alexandria, Egypt. Eratosthenes wrote down the angle of the shadow cast by the stake. Around the same time in
Syene (todays Aswan, Egypt), another person drove a stake into the ground—but this stake cast no shadow. Eratosthenes calculated the circumference of the Earth by using the angle of the first shadow and the distance between
Syene
and Alexandria. Knowing what we have learned through technology, today’s geographers found that Eratosthenes measurements were off by about 15 percent. With the simple tools that were available to Eratosthenes - he was remarkably accurate. He was one of the earliest geographers to use tools and critical thinking to measure and describe the earth.Slide3
Eratosthenes:
1
st
Person to calculate the circumference of the EarthSlide4
The oldest known map is about 2,500 years old. This map is a Babylonian clay tablet. It is about four inches high and shows the Babylonian world surrounded by water. Mapmaking has evolved over the centuries but the maps function has remained the same. The function of the map is to show locations of places, landforms, and bodies of water, and where they are in relation to other parts of the earth.Slide5
3D depiction of the Earth. A globe is a sphere that provides us a way to see the Earth as it moves through space. Globes are not very practical because they are not easily portable.
GlobeSlide6
Three Dimensional
Globes help Geographers study the world
What are some advantages/disadvantages of using globes?Slide7
Globes provide a proportional view of the earth as it travels through space.
They are not easily portable.
You can only see half of it at a time.
ADVANTAGES/DISADVANTAGESSlide8
Cartographers
make maps. Maps are two-dimensional graphic representations of selected parts of the earth’s surface. A map is easily portable and can be drawn to any scale needed. The disadvantage of a map is that distortion occurs as the earth’s surface is flattened to create the map
MAPSlide9
Advantages/Disadvantages
Easily portable
Can be drawn to any scale needed
Distortion occurs as maps are flattened
A map projection is a way of drawing the earth’s surface that reduces distortion caused by presenting around earth on flat paper.Slide10
Map projection:
Earth’s curved surface on a flat map.Slide11
A map that focuses on one particular idea or theme.
The map to the right of the slide focuses on Ireland’s precipitation.
Thematic MapSlide12
MAP SCALE
Size of scale is determined by detail.
Large scale maps are needed to show many details. LARGE SCALE = LARGE DETAIL.
Small scale maps are needed when fewer details are shown. SMALL SCALE = SMALL DETAIL.
What are some examples of places that would need a large scale?
What are some examples of places that would need a small scale?Slide13
THEMATIC MAPS:
Focus on specific types of information. (example: population density, vegetation, weather maps, resources, amusement parks, etc…)Slide14
QUALITATIVE MAPS: Use colors, symbols, dots or lines to help you see a pattern.Slide15
NAVIGATIONAL MAPSlide16
THE SCIENCE OF MAPMAKING
SURVEYING
Surveyors observe, measure, record what they see in a specific area.
They use remote sensing (gathering data from a distance) to do this.
Remote sensing includes:
Aerial photography
Satellite imagingSlide17
Geographers study history to help them understand what places looked like in the past and how those places have changed over time.
History is divided into blocks of time known as periods:
Decade: a period of 10 years.
Century: a period of 100 years.Millennium: a period of 1000 years.