Continuing on the subject of maps, I recently came across a fascinating post on Atlas Obscura, describing the various kinds of maps used by cartographers. As Harvard landscape architecture professor and author Jill Desimini explains, maps must retain geographic fidelity, scale, and projection. However, the best ones, she continues, also have a visual clarity and graphic integrity equivalent to any art form.
Desimini and fellow Harvard professor Charles Waldheim explore 10 conventions that are essential to map making in their recently published book, Cartographic Grounds: Projecting the Landscape Imaginary. The book contains 275 pages of vivid maps with explanations detailing the methods used by their cartographers.
These conventions can help lead to more beautiful and informative maps, adding to the richness and diversity of representations of our world.
1. Sounding / Spot Elevation
This cartographic component includes two measurements for showing depths and heights above and below sea level. “Soundings” pinpoint depths of water and are noted by a number on a nautical chart, while “spot elevations” are the numbers that show the position and altitude.
In this map, Alexander Dallas Bache, a cartographer who ran the NOAA Coast Survey from 1843 to 1867, rendered the San Francisco urban coastline, using spot elevations to depict the water’s edge.
2. Isobath / Contour
Isobaths and contours are lines that connect points of equal value on maps, showing the morphology of the ground. The map of the University of Puerto Rico Botanical Gardens show a series of color ribbons and swaths that represent the topography.
3. Hachure / Hatch
This convention is a series of short lines that perpendicularly fill the space between contours and show slope, shadow, relief, and texture. Topographer Gustavus Bechler designed this map of the sources of Snake River, which has hachures, or reliefs, that are “particularly soft and warm, allowing ridgelines to dissipate into plateaus,” Desimini and Waldheim write.
4. Shaded Relief
Shaded relief is the depiction of shadows with tonal gradients. This marks changes in elevation and landform in raised relief maps and models. The Blue Slabs painting from late architect Zaha Hadid’s The Peak shows an abstract block colorization of the sprawling city of Hong Kong. The shadows make the building beams look like they are flying from the cliffs.
5. Land Classification
This is the taxonomic method of describing spatial distribution of vegetation and agronomic land uses. It’s used to distinguish types of soil, vegetation, and activity. The image of greater New Orleans codes different projected land uses with colors and patterns.
This technique helps distinguish space, usually urban spaces, from other entities, such as a building and the rest of the urban environment. In this 1962 map created by German cartographer and graphic artist Herman Bollmann, the aerial view of New York City shows the high-rises without blocking the ground and streets. The map was made for the New York World’s Fair.
7. Stratigraphic Column
Stratigraphic columns rely on color to show locations of rocks, visualize geologic time, and signify soil and sediment type. This extremely elaborate 1890 geological map of Paris shows known, invented, and hidden layers of underground rock with the city above.
8. Cross Section
A cross section is a vertical slice through the Earth’s surface, which specifies elevation, depth, and structural and material composition.
9. Line Symbol
This cartographic convention marks off boundaries, borders, property lines, rivers, infrastructures, and routes. In this map of the Appalachian Trail in Maine, lines distinguish roads and trails from streams and mountains
10. Conventional Sign
These are symbols or icons that denote different entities on map, such as schools, churches, highways, restaurants, or airports. This map of the Ezo region of Japan (now Hokkaido), illustrated in 1854, includes yellow circles along the coast line that mark cardinal directions.