The hook
Maps are purposeful abstractions — every map type drops some information to highlight something else. The working skill is knowing which map type does what: planimetric vs. topographic, cadastral vs. thematic, hard-copy vs. digital, large-scale vs. small-scale.
Memorize these
Concepts that show up on the exam
Planimetric map
Shows features in plan view — buildings, roads, water, vegetation outlines — but NO elevation. Quick to produce, useful as a base layer.
Topographic map
Planimetric + contour lines + spot elevations. The classic USGS quad. Used for design and analysis.
Cadastral map
Shows parcel boundaries, ownership, dimensions, easements. Maintained by counties; a primary source for boundary work.
Thematic map
Shows the spatial distribution of a single variable (zoning, soils, flood, climate). Often choropleth (colored regions) or isoline (contours of the variable).
Orthophoto
An aerial photo that has been rectified so distances on the photo are true distances on the ground. Used as an accurate base layer; quasi-cartometric.
Plat
A surveyor-prepared map showing a subdivision's lots, blocks, streets, easements. Recorded with the county; legally controlling for the parcels it creates.
Scale (representative fraction)
Ratio of map distance to real-world distance: 1:1,200, 1:24,000. Smaller fractions = LARGER scale (more detail). 1:24,000 (USGS quad) is "small scale" relative to a 1:600 site plan.
Digital vs. paper
Digital: GeoTIFF, KMZ, shapefile, geodatabase. Paper: still legally significant for plats. Digital data is the working medium; paper is the archival.
| Scale | Typical use | Detail captured |
|---|---|---|
| 1:200 — 1:1,000 (LARGE) | Site plans, building layouts, ALTA surveys | Individual building corners, utilities, trees |
| 1:1,200 — 1:6,000 | Subdivision maps, neighborhood plans | Streets, lots, structures |
| 1:24,000 (USGS quad) | Regional planning, hiking, watershed | Roads, contours, water features |
| 1:100,000 — 1:1M (SMALL) | State or national overviews | Major highways, state boundaries |
Don't fall for these
What trips people up
Calling 1:24,000 "small scale" in casual speech
Cartographic convention: "small scale" = small representative fraction = covers a LARGE area with little detail. 1:24,000 IS small scale relative to a site plan. Casual usage often gets this exactly backward.
Treating an orthophoto as a survey
Orthophotos can be cm-accurate when properly produced, or meters-off when not. Don't use one as a boundary source without knowing its quality. ALTA surveys EXCLUDE features known only from imagery.
Confusing thematic with cadastral
A "zoning map" is THEMATIC — it shows zoning categories. The underlying parcel boundaries on it are derived from cadastral data but are NOT authoritative for boundaries. Boundary work needs the recorded plat.
Test yourself
How well did it stick?
A quick 5-question check on Types of Maps. See where you stand and what to review.