1. Topographic Base Maps Objective – Displays surface features (topography, roads, lakes & river, cultural features) and a grid system (TRS, UTM, Lat/Lon) that allow one to readily locate the geologic features portrayed Objective – Displays surface features (topography, roads, lakes & river, cultural features) and a grid system (TRS, UTM, Lat/Lon) that allow one to readily locate the geologic features portrayed Best choice of base map is largely dependent on the map scale Best choice of base map is largely dependent on the map scale 1:24,000 scale (7.5’ USGS quadrangle)1:100,000 scale (30’x60’ USGS sheet) GEOL 3000

2. Global Grid – Latitude-Longitude

3. Map Projections Mercator Transverse Mercator Conical Polyconic

4. Universal Transverse Mercator (UTM) Grid Two Versions of North American Datum (NAD) grid – 1927 and 1983

5. Surveyed Grid Township, Range, Section Section ~1 sq. mile Township ~36 sq. miles

6. Potential Misfit of Surveyed Sections

7. Grids on Topographic Maps Latitude Longitude Township Boundary

8. Other Information on Topographic Maps

9. Elements of the Topographic Map USGS Topographic Map Symbol Website

10. Topographic Contour Lines connects points of equal elevation Rules: Lines never cross Lines never end Lines “V” upstream Lines encircle hills and depressions

11. Reading Topography

12. Creating a Topographic Profile

13. Intersection of Topography and Geology

14. Standard Topographic Basemap Scales 1° x 2 ° Sheets 1:250,000 1” = 4 miles 7.5’ Quadrangles 1:24,000 1” = 2000 feet See DNR Maps Website for MN topo maps Also: 30’x60’ sheets, 1:100,000, 1”=1.5 miles