Types of Maps Chapter 3, Section 3 Objectives Explain how elevation and topography are shown on a map. Describe three types of information shown in geologic maps. Identify two uses of soil maps.

Topographic maps Show the surface features, or topography, of the earth. Shows both natural and constructed features.

Making A Topographic Map A topographic map shows the elevation, or height above or below mean sea level (set at 0), the point midway between the highest and lowest tide levels.

Advantages of Topos Provides more detailed information about the surface of the earth (size, shape, elevation) than a drawing does.

Elevation on Topos Shown by contour lines, isograms that connect points that pass through areas of equal elevation. The shape of the contour lines reflect the shape of the land.

Contour Interval The difference in elevation between each contour line. Chosen by a cartographer suited to the scale and relief of the land.

Contour interval ???

Relief The difference in elevation between the highest and lowest points on a map. High relief areas have large contour intervals, areas of low relief have small contour intervals.

Index Contours Every fifth contour line is bolder than the others and is marked with its elevation.

Altitudes Must be estimated between contour lines. Exact elevations are shown by an x and are labeled.

Landforms on Topos Closely spaced contour lines represent a steep slope. Widely spaced contour lines represent a gentle slope. Concentric circles of contour lines indicate a hilltop. Concentric circles of hachured lines indicate a depression. The lines point downslope.

BASIC RULES Contour lines never cross. Contour lines never split. Contour lines form a V-pattern crossing a stream and always point upstream.

Topo Symbols (p. 876) – Color Coded Constructed features – black Contour lines – black or brown Major highways – red Water – blue Forests - green

Contour Lines - Describe the features

Topographic Features

Computer enhanced topographic maps

Graphical Display of the Federal Township and Range System (Not In Text) (Developed by the federal government after the Louisiana Purchase, maps areas west of Ohio)

Principal Meridians and Baselines The largest grouping in the township which is named in reference to a principal meridian (the vertical line) and a baseline (the horizontal line). T2N, R1E refers to Township 2 North (of the baseline), Range 1 East (of the Principal Meridian)

Subdivisions of Townships (Sections) Each township contains 36 sections, each one mile square. This is equal to 640 acres. They are numbered in the order as noted to the right.

Section Subdivisions Sections are then divided into progressively smaller subsections by dividing by halves or quarters.

Geologic Maps Show the types of rocks in a given area and other geologic features (faults, folds, etc.). Produced on top of a base map that shows the surface features of the area.

Rock Units on Geologic Maps Geologic unit: A volume of specific rock type and age, distinguished by color and printed symbols: AGE unit name/rock type Ocf = Ordovician, Craig Formation (pink for igneous rock)

Other Structures on Geologic Maps Contact line: The line where two geologic units meet (a contact).

Two Main Types of Contacts Depositional: Shows where one rock layer formed over another. Fault: Fractures where rocks can move past each other.

Strike and Dip Strike: The direction in which rock beds run. Dip: The angle at which the beds tilt.

Soil Maps Constructed to classify, map and describe soils Based on soil surveys commonly done for a county National Resources Conservation Agency (NRCS), part of the USDA, compiles soil data and the distribution of soils in United States

Soil Surveys and Uses of Soil Maps Soil Survey – three main parts Text – geology, topography, and climate of mapped area Tables – types and volumes of soils in the area Two types of soil maps in surveys: general locating soil types and detailed showing specific soils in an area Valuable tools for agriculture and soil management Conservation and use of soil and in planning sites for development

Other Types of Maps Maps are useful to scientists in every branch of Earth Science Satellite Imagery from Space Groundwater Precipitation Ocean Temperatures

Survival of the fittest: ASSIGNMENT Directed Reading 3.3 Key Terms Due beginning of period tomorrow. Lab Tues.-Wed. TEST – Chapter 3 Thursday Survival of the fittest: You gonna make it?