Geography: Maps, Spatial Patterns, and Projections
Maps and Spatial Patterns
Geographers emphasize spatial patterns: the arrangements of things studied in repeated sequences of events or processes that create them.
Learning to recognize and use geographical patterns is a key tool for geographers.
Advances in geospatial data, computer data, and the variety of maps available influence everyday life via smartphones and apps that allow viewing, interaction, modification, and showing our own location within maps.
Maps are the most important tool of a geographer and help organize complex information; no tool communicates spatial information more effectively.
Maps are essential for highlighting and analyzing patterns.
Two broad categories of maps:
Reference maps
Thematic maps
Reference Maps
Designed for people to refer to for general information about places.
Political maps show and label human-created boundaries and destinations (countries, states, cities, capitals).
Physical maps show and label natural features (mountains, rivers, deserts).
Road maps show and label highways, streets, and alleys.
Plat maps show and label property lines and details of land ownership.
Thematic Maps
Thematic maps show spatial aspects of information or a phenomenon.
Four common types described below (in order of appearance):
Choropleth maps
Dot distribution maps
Graduated/proportional symbol maps
Isoline maps
Cartograms (and a note on a related term mentioned in the transcript)
Choropleth maps
Use various color shades of one color or patterns to show the location and distribution of spatial data.
Often show rates or other quantitative data in defined areas (e.g., the percentage of people who speak English).
Dot distribution maps
Show the specific location and distribution of something across a map.
Each dot represents a specific quantity.
Examples: one dot might stand for one school building or for millions of people who own dogs.
Any symbol can be used instead of dots (e.g., triangles, house outlines, cows).
Graduated symbol maps (proportional symbol maps)
Use symbols of different sizes to indicate different amounts of something.
Larger symbol sizes indicate more of the phenomenon; smaller indicate less.
The map key determines the exact amount represented by a symbol.
Symbols may overlap since they are centered over the data location.
Also called proportional symbol maps.
Isoline maps
Use lines that connect points of equal value to depict spatial variations.
Where lines are close together, the map shows rapid change; where they are farther apart, the phenomenon is relatively the same.
Most common type of isoline maps are topographic maps, popular among hikers.
Points of equal elevation are connected to create contours that depict surface features.
Other examples of isoline maps include weather maps showing changes in barometric pressure, temperature, or precipitation across space.
Cartograms (and related terminology in the transcript)
In a cartogram, the sizes of countries, states, counties, and other areas are shown according to some specific statistic.
Example given: a cartogram of world population can make Canada and Morocco appear roughly the same size because they have similar populations (~35,000,000 people).
Although Canada is more than 20 times larger in area, the cartogram represents size by population, illustrating how a variable can substitute for geographic area.
Distance and distribution are visible as in a traditional map, but the area sizes reflect the data variable.
The transcript uses the term "Chrodograms" in one place, which appears to be a mis-spelling of cartograms; cartograms are the correct term here.
Scale
Nearly every map is smaller than the portion of the Earth's surface it represents; a map is a reduction of real land area.
Scale is the ratio between the size of things in the real world and the size of those same things on the map.
Three types of scale:
Cartographic scale
Geographic scale
Scale of the data represented on the map
Cartographic scale
Refers to how the map communicates the ratio of its size to the size of what it represents.
Example: 1\text{ inch} = 10\text{ miles} (one inch on the map equals ten miles on the ground).
A ratio example: 1:200{,}000 (one unit on the map equals 200,000 of the same unit in reality).
Example elaboration: 1\text{ inch on the map} = 200{,}000\text{ inches on the ground} \approx 3.15\text{ miles}
A line on the map may indicate a distance with a linear or graphic scale.
Small-scale maps show a larger area with less detail.
Large-scale maps show a smaller area with more detail.
Examples: global-scale view at night (less detail, large area) vs. North America at night (larger detail, smaller area).
Geographic scale
Not explicitly differentiated in the transcript beyond the three types; conceptual understanding: geographic scale connects the map’s representation to real-world geography.
Scale of the data represented on the map
Indicates that the data variable itself (e.g., population, language usage) is what is scaled, which may affect how the map is interpreted beyond spatial extent alone.
Spatial Patterns and Spatial Concepts
Spatial patterns describe the general arrangement of phenomena on a map.
Tools and concepts used to describe patterns include: location, direction, distance, elevation, and distribution.
Location
Absolute location: the precise spot according to a reference system (global grid of latitude and longitude).
Latitude: distance north or south of the equator.
The Equator is designated as zero degrees and the poles as ninety degrees north and ninety degrees south.
Longitude: distance east or west of the prime meridian (through Greenwich, England; designated zero degrees).
The opposite side of the globe from the prime meridian is 180 degrees longitude.
The international date line roughly follows this line but deviate to accommodate boundaries.
Example: the absolute location of Mexico City is 19° N, 90° W.
Relative location: description of where something is in relation to other things; often described in terms of connectivity and accessibility (roads, links, interaction).
Relative location can change over time as accessibility changes (e.g., ghost towns near water sources or trade routes that dried up).
Direction
Used to describe where things are relative to each other.
Cardinal directions: northeast, southeast, southwest, northwest; common to describe location.
On most maps, north is at the top, but check directional clues on the map.
Distance
Absolute distance: measured in feet, miles, meters, or kilometers (e.g., the distance from home to school is 2.2 miles).
Relative distance: distance in terms of time or money, dependent on mode of travel (e.g., 10 minutes by car or 25 minutes by walking).
Elevation
Elevation is the height above sea level (measured in feet or meters).
Elevation can impact climate, weather, and agriculture.
Generally, higher elevation = cooler temperatures; very high elevations can limit crop growth.
Elevation is often shown on maps with contour lines.
Distribution
Distribution describes how a phenomenon is spread over an area.
Geographers look for patterns or the general arrangement to infer causes or effects.
Common distribution patterns:
Clustered or agglomerated: grouped together (e.g., restaurants in a mall food court; cities along a border).
Linear: arranged in a straight line (e.g., towns along a railroad line).
Dispersed: spread out over a large area (e.g., large malls in a city).
Circular: equally spaced from a central point (e.g., homes of people who shop at a store).
Geometric: regular arrangement (e.g., grid-like squares or blocks formed by roads in the Midwest).
Random: no apparent order (e.g., distribution of pet owners in a city).
Projections and Map Distortions
Because the Earth is a sphere and maps are flat, all maps distort some aspect of reality via projection.
Cartographers choose projections based on what they want to preserve: area, shape, distance, or direction; preserving one quality requires compromising others.
The Mercator projection (quoted in the transcript as Mercador or Mercadur) is famous for navigation because lines of constant compass bearing are straight and easy to follow.
Weakness of Mercator on a global scale: it exaggerates the size of landmasses away from the equator, making high-latitude regions appear larger than they are (e.g., Greenland appears similar in size to Africa, when Africa is about 14 times larger).
This distortion can contribute to political and economic bias, possibly reinforcing perceptions of power and wealth inequalities.
All projections have strengths and weaknesses; the goal is to understand these trade-offs and choose the projection best suited for the map’s purpose.
Real-World Relevance and Implications
Maps enable spatial reasoning and decision-making in everyday life (navigation, planning, resource allocation).
Understanding projections helps critically evaluate maps, recognize bias, and avoid misinterpretation of data.
The choice of map type (reference vs thematic) and the appropriate projection depend on the goal (e.g., navigation vs comparing populations).
Ethical implications: projection-induced biases can influence political opinions and resource distribution; awareness of distortions helps mitigate misperceptions.
Connections to Foundational Principles
The concept of scale connects map representation to the real world, linking geography with mathematics through scale ratios and units.
Spatial patterns (location, distance, direction, elevation, distribution) form the core framework for spatial analysis in geography.
The trade-offs in map projections reflect broader trade-offs in representation and measurement across disciplines.
Quick Reference Formulas and Examples
Map scale examples:
Cartographic scale example: 1\text{ in} = 10\text{ mi}
Ratio scale example: 1:200{,}000
Linear scale example: 1\text{ in} \rightarrow 200{,}000\text{ in} \approx 3.15\text{ miles}
Absolute location example: Mexico City at approximately \text{Lat}=19^{\circ}N, \ \text{Lon}=90^{\circ}W
Cartogram concept: areas sized by a statistic (e.g., population) rather than geographic area; Canada and Morocco could appear similar in size on a population cartogram if populations are similar (~3.5\times 10^{7} people).
Elevation example: Mount Everest summit > 29{,}000\text{ ft} above sea level.
Notes
Be mindful of potential typos in source terms (e.g., Mercator projection is sometimes misspelled in informal texts as "Mercedur" or "Mercador"). The standard term is Mercator.
Practice interpreting multiple map types and choosing appropriate projections for different analyses and decisions.