Introduction to Maps and Types of Maps Chapter Notes | AP Human Geography - Grade 9 PDF Download

Introduction

This chapter notes xplores the evolution of cartography by comparing early and contemporary maps, focusing on map scale and projection. It examines how maps represent Earth’s surface through scaling techniques and projection methods, addressing the challenges of depicting a spherical globe on a flat surface. The content highlights the significance of choosing appropriate scales and projections to balance accuracy and detail for various mapping purposes.

Early Maps vs Contemporary Maps

Map Scale and Projection

• Have you ever wondered why maps aren’t the same size as the regions they depict, like a map of America or the entire world? The answer lies in map scaling, which allows cartographers to create manageable representations of large areas.
• A map scale defines the relationship between distances shown on a map and the corresponding distances on Earth’s surface.
• Map scales differ widely based on the map’s purpose and size. Large-scale maps, such as those for cities or streets, use a smaller scale to display intricate details. Small-scale maps, like those of the world or regions, use a larger scale, covering vast areas with less detail.
• The choice of map scale is critical, as it influences the map’s accuracy and the level of detail it can convey. Selecting the right scale is essential to meet the map’s intended use and the required detail.
• The three primary types of map scales are:
  1. Ratio Scale
     • Example: 1 : 25,000
     • The left number represents units of distance on the map.
     • The right number indicates units of distance on Earth’s surface.
     • For instance, 1 inch on the map corresponds to 25,000 inches in reality.
  2. Written Scale
     • Example: “1 inch represents 1 mile”
     • Describes the scale relationship in words for clarity.
  3. Graphic Scale
     • A bar line on the map visually indicates the actual distance covered.
• Scaling explains why maps are not as large as the areas they represent, but how does a flat, two-dimensional map accurately depict the spherical Earth? This brings us to map projections.
• A map projection is a technique for translating the Earth’s curved, three-dimensional surface onto a flat map. Since the Earth is a sphere, creating a perfectly accurate flat map without some distortion is impossible. Projections aim to reduce these distortions based on the map’s purpose and the region being represented.
• There are numerous map projections, each with its own advantages and limitations. Some widely used projections include:
  • Mercator Projection: Frequently used for navigation, this projection preserves angles, aiding in plotting straight-line courses. However, it exaggerates the size of landmasses near the poles, making them appear disproportionately large.
  • Peters Projection: Designed to maintain accurate relative sizes of countries with minimal area distortion, but it distorts shapes and distances, rendering it less ideal for navigation.
  • Equal-Area Projection: Preserves the area of landmasses accurately but distorts their shape and distance.
• Choosing the right projection is vital, depending on the map’s purpose and the characteristics of the mapped area. No projection can perfectly represent all aspects of the Earth’s surface, so compromises are always required.
• Cartographers must decide which of the following aspects to prioritize, as distortions may occur in:
  • The shape of a region, which may be altered.
  • The distance between two points, which may be inaccurate.
  • The relative size of different areas, which may be misrepresented.
  • The direction, which may be distorted.

Examples of Projection Families

• Cylindrical Projections: Suitable for equatorial regions and global maps, but they introduce significant distortions.
• Conical Projections: Less distorted at mid- and high latitudes compared to cylindrical projections.
• Azimuthal (Planar) Projections: Effective for polar regions with minimal distortion near the poles.

Two Important Types of Projections

Robinson Projection

• The Robinson projection, developed by Arthur H. Robinson in the 1960s, is a modified version of the Mercator projection. It aims to address some of the Mercator’s distortions, particularly the exaggerated sizes of polar regions, while retaining some of its beneficial features.
• As a compromise projection, the Robinson projection seeks to balance distortions inherent in all map projections. It is not flawless and still distorts size, shape, and distance to some extent. 
• However, it is often regarded as more visually appealing and practical than the Mercator projection for purposes like world maps and atlases.
• The Robinson projection is commonly employed for world maps and maps covering large regions, as it provides a reasonable representation of the entire Earth. 
• It is less suitable for small-scale maps, such as city or street maps, due to excessive shape and distance distortions.
  • Focuses on depicting oceans accurately.
  • Landmasses appear smaller than in some other projections.

Mercator Projection

• Introduced by Gerardus Mercator in 1569, the Mercator projection is a cylindrical projection where meridians (longitude lines) and parallels (latitude lines) form a grid of straight, perpendicular lines.
• A key feature of the Mercator projection is its increasing distortion of object sizes from the Equator toward the poles. Landmasses like Greenland and Antarctica appear significantly larger than their actual size, while equatorial regions are underrepresented.
• The Mercator projection remains popular in navigation and online mapping systems due to its simplicity and utility in plotting straight-line courses. 
• However, it is not an accurate depiction of the Earth’s surface, prompting the development of alternatives like the Peters or Gall-Peters projections to address these inaccuracies.
  • Maintains accurate shape and direction.
  • Produces a rectangular map.
  • Significantly distorts the size of polar regions.

Geographic Grid

• The Earth’s surface is overlaid with an imaginary grid system that enables precise location identification.
• Grid patterns consist of regularly arranged objects or features in a structured, grid-like format. 
• These patterns appear in various contexts, including:
  • Urban Planning: Many cities are designed with a grid layout, organizing streets and blocks systematically.
  • Agriculture: Techniques like square foot gardening use grid patterns for crop planting.
  • Landscaping: Grid patterns create formal, structured designs in gardens or parks.
  • Computer Graphics: Grids are used to align objects or create structured backgrounds.
• Grid patterns are favored for their simplicity, clarity, and efficient use of space. However, they can appear rigid and lack aesthetic variety.
  • Parallels: These are circular arcs around the Earth, running parallel to the Equator.
    • The location of parallels is measured by latitude.
  • Latitude → LAP → Horizontal: Latitude lines are horizontal, like the lap of a person sitting down.
    • “LAT is FAT” – a mnemonic to remember latitude’s horizontal orientation.

Latitude

​Latitude measures a location’s position on Earth’s surface in degrees north or south of the Equator.

Key Terms

• Contemporary Maps: Modern maps employing advanced technologies like satellite imagery, Geographic Information Systems (GIS), and interactive features to represent geographical data with real-time analysis and visualization capabilities.
• Early Maps: Historical maps created before modern cartographic methods, used for navigation, exploration, and understanding geography, depicting landforms, trade routes, and territories.
• Equal-Area Projection: A map projection that preserves the relative sizes of geographical areas, ensuring proportional representation, though it may distort shape and distance, useful for spatial comparisons.
• Geographic Grid: A network of intersecting latitude and longitude lines used to pinpoint locations on Earth’s surface, essential for navigation and cartography, with latitude running horizontally and longitude vertically.
• Graphic Scale: A visual bar scale on a map illustrating the relationship between map distances and actual ground distances, aiding users in measuring real-world distances.
• Latitude: A geographic coordinate measuring a location’s distance north or south of the Equator in degrees, represented by horizontal parallels, critical for mapping and navigation.
• Longitude: A geographic coordinate indicating a point’s east-west position on Earth, measured in degrees along meridians from pole to pole, essential for precise location identification.
• Map Scale: The ratio between distances on a map and actual distances on Earth’s surface, determining the map’s detail and accuracy, crucial for various mapping purposes.
• Mercator Projection: A 1569 cylindrical projection by Gerardus Mercator that preserves angles for navigation but distorts sizes, especially near the poles, widely used in online maps.
• Meridian: An imaginary line of longitude running from the North to South Pole, used to measure east-west positions, integral to the geographic grid and navigation.
• Parallel: A line of latitude running horizontally around the Earth, measuring north-south positions, forming part of the geographic grid for accurate location referencing.
• Peters Projection: A cylindrical projection prioritizing accurate area representation, minimizing size distortion but altering shapes and distances, offering a more equitable view of global landmasses.
• Projection: The method of transforming Earth’s curved surface onto a flat map, introducing unavoidable distortions in area, shape, distance, or direction, chosen based on map purpose.
• Ratio: A numerical expression of the relationship between two quantities, used in map scales to indicate how map distances correspond to real-world distances, e.g., 1:100,000.
• Robinson Projection: A 1960s compromise projection by Arthur H. Robinson, balancing size and shape distortions for visually appealing world maps, minimizing polar exaggerations.
• Written Scale: A verbal statement of a map’s scale, such as “1 inch equals 1 mile,” clearly explaining the relationship between map and ground distances.