topographic base maps
DESCRIPTION
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 Best choice of base map is largely dependent on the map scale. - PowerPoint PPT PresentationTRANSCRIPT
Topographic Base MapsTopographic Base Maps Objective – Displays surface features (topography, Objective – Displays surface features (topography,
roads, lakes & river, cultural features) and a grid roads, lakes & river, cultural features) and a grid system (TRS, UTM, Lat/Lon) that allow one to system (TRS, UTM, Lat/Lon) that allow one to readily locate the geologic features portrayedreadily locate the geologic features portrayed
Best choice of base map is largely dependent on Best choice of base map is largely dependent on the map scale the map scale
1:24,000 scale (7.5’ USGS quadrangle)1:100,000 scale (30’x60’ USGS sheet)
GEOL 3000GEOL 3000
Global Grid – Latitude-LongitudeGlobal Grid – Latitude-Longitude
Map ProjectionsMap Projections
Mercator
Transverse Mercator
Conical
Polyconic
Universal Transverse Mercator Universal Transverse Mercator (UTM) Grid(UTM) Grid
Two Versions of North American Datum (NAD) grid – 1927 and 1983
Surveyed Grid Surveyed Grid Township, Range, SectionTownship, Range, Section
Section ~1 sq. mile
Township ~36 sq. miles
Potential Misfit of Surveyed Potential Misfit of Surveyed SectionsSections
Grids on Topographic MapsGrids on Topographic Maps
Latitude Longitude
TownshipBoundary
Other Information on Topographic Other Information on Topographic MapsMaps
Elements of the Elements of the Topographic Topographic
MapMap
USGS Topographic Map Symbol Website
<click here>
Topographic Contour LinesTopographic Contour Linesconnects points of equal elevationconnects points of equal elevation
Rules:Rules:
• Lines never cross
•Lines never end
•Lines “V” upstream
•Lines encircle hills and depressions
Reading TopographyReading Topography
Creating a Creating a Topographic Topographic
ProfileProfile
Intersection of Topography and Geology Intersection of Topography and Geology
Standard Topographic Basemap ScalesStandard Topographic Basemap Scales
1° x 2 ° Sheets1:250,000
1” = 4 miles
7.5’ Quadrangles1:24,000
1” = 2000 feet
See DNR Maps Website for MN topo maps<click here>
Also: 30’x60’ sheets, 1:100,000, 1”=1.5 miles