people.
Dot Density
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Let’s try a different thematic map that will let us be a bit more specific.
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A dot density map uses a dot to represent a key feature or attribute.
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The cartographer decided that each dot on this map represents 100,000 people.
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So while the choropleth map showed the general population spread out over an entire country,
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this dot density map has more granularity and shows where within a country people live.
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More or less.
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We can see the coasts of Brazil have more dots -- and more people.
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But take a look at the Sahara or Siberia.
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No one lives exactly where those dots are!
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The cartographer also decided where to place each dot to summarize population data.
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But it’s a simplification that could mislead someone if they're not paying close attention
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like we are!
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A dot doesn’t necessarily mean 100,000 people live exactly there.
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Cartographers are always trying to make maps easily readable, but all the choices they
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make can influence accuracy.
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For example, if we changed how our dot density map is projected, or how the 3D Earth was
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flattened into 2D, the size and shape of the continents would shift, and so would the dots.
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We might accidentally imply some areas have a closer population density while others are
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more spread out.
Cartogram
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Our last thematic map for today is a cartogram map, which uses size to compare data -- like
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population density -- regardless of the actual space these regions take up on the Earth's
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surface.
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With this map, the really populous countries are giant, while ones with smaller populations
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are tiny.
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But it looks weird to us or at least me, because we're used to maps that tell us something
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about the physical space that countries and continents take up.
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India has a much bigger population, but in real life Australia is a muuuuch larger country
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-- it’s about 7.7 million square kilometers while India is less than half the size with
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3.28 million square kilometers.
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Each of these thematic maps uses a different lens to tell the story of the world population.
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Different maps represent data in different ways.
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And the more information a geographer has, the better interpretations they can make about
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a particular story -- like human population.
Perception of Reality
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Of course, there are many, many more stories to tell, so there are many, many more maps.
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And by helping us visualize data across space, maps actually shape our perception of reality
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too!
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Alright, that sounds a bit melodramatic.
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But every map was made by a person making choices.
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And those choices (however thoughtful, or simple, or unintentionally biased) have an
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impact on how we imagine the world.
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Like, we’re so used to seeing north at the top of a map and south at the bottom.
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But why?
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Well, that's a choice made by a cartographer.
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Other cartographers tried something different with a Fuller projection that unfolds the
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Earth and ends up with a completely different orientation without distorting anything.
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This map doesn’t have Greenland at the very top of the map, like we might be used to.
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There’s more than one way to represent Earth.
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By thinking about what a map was supposed to be used for, we can spot these obvious
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or not-so-obvious choices made by cartographers.
Stick Charts
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For centuries humans have been using maps as navigational tools to help us understand
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our physical surroundings.
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Stick charts like these are made of fibers from coconuts and shells that were developed
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by mariners from the Marshall Islands.
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These charts weren’t used to navigate exactly the same way that we use maps today.
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They weren’t carried along in the boats, but studied and memorized to get a better
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idea of the islands, waves, winds, and currents in the Pacific Ocean.
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Stick charts were personal -- mariners had their own stick charts that they used to get
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back to places they’d visited.
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Kinda like my mental map to my favorite coffee shop.
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These charts were someone’s own perception of the space in their individual world.
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Maps can also be used politically, and the choices about where to draw borders on a map
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are giving spaces a national identity.
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For example, there's a dispute over territory in Antarctica and some nearby islands that’s
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currently on pause thanks to a 1959 treaty.
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Originally the 12 countries whose scientists had been conducting research on the continent
List here any words/vocabulary you hear that you don’t understand or know what they mean.
1. Thematic map: A map that emphasizes a particular theme, such as population density or climate patterns.
2. Cartographer: A person who creates maps.
3. Choropleth map: A type of thematic map that uses different shades or patterns to represent data in different areas.
4. Granularity: The level of detail or specificity in a dataset or map.
5. Projection: The method used to represent the curved surface of the Earth on a flat surface.
6. Accuracy: The degree to which the information on a map corresponds to the actual reality.
7. Cartogram: A type of thematic map that distorts the size of regions to represent a particular variable, such as population density.
8. Perception: The way in which something is understood or interpreted.
9. Melodramatic: Exaggerated or overly emotional.
10. Biased: Having a preference or prejudice that influences one's decision-making.
11. Oriental: The direction toward the rising sun or the East.
12. Fuller projection: A type of map projection that attempts to minimize distortion by using a polyhedral representation of the Earth's surface.
13. Navigational: Relating to the process of determining and following a route or direction.
14. Marshall Islands: A country in the Pacific Ocean consisting of multiple islands.
15. Memorized: To commit something to memory by repetition or practice.