Chapter 1, Lesson 2, Topographic and Geologic Maps 1 -What are Topographic and Geologic Maps? *What are topographic maps? -They are specialty maps used to show specific features such as changes in elevation geologic characteristics. *Topographic maps use lines of equal elevation to show the shape of Earth’s surface. *They show natural features, such as mountains, valleys, rivers, lakes, and coastlines. *They also show cultural features, such as buildings, roads, and towns.

Topographic map 2

Chapter 1, Lesson 2, Topographic and Geologic Maps 3 -What are contour lines? -Contour lines are lines drawn on maps to join points of equal elevation. -On topographic maps, contour lines make it possible to measure such things as the height of a mountain, and the depth of the ocean. -The contour interval is the distance in elevation between contour lines that are next to each other. -If the contour interval were 20 feet, then the change in elevation after 5 contour lines would be 100 feet.

Contour lines 4

Chapter 1, Lesson 2, Topographic and Geologic Maps 5 *What are topographic profiles? *They are profile views of a topographic map. *A topographic profile view looks as though you were standing on Earth’s surface and looking toward the horizon.

Chapter 1, Lesson 2, Topographic and Geologic Maps 6 -What kinds of symbols on topographic maps? -On USGS (United States Geological Survey) maps: Lakes, streams, oceans, and irrigation ditches are in blue. Vegetation is always green. Land grids and important roads are red. Smaller roads, trails, railroads, boundaries, and other cultural features are in black. USGS symbols, also, use a variety of symbols to display information: Individual houses may be shown as black squares. Closely spaced contour lines show steep slopes. Widely spaced lines show areas where land is relatively flat.

Chapter 1, Lesson 2, Topographic and Geologic Maps 7

Chapter 1, Lesson 2, Topographic and Geologic Maps 8 *What are geologic maps? -What are geologic formations? *Geologic maps represent the geology of an area. *They can be used to locate valuable minerals or for understanding earthquakes. -A geologic formation is a 3-dimensional, or volume, of a certain kind of rock of a given age range. -For example, sandstone of one age might be represented by light yellow and sandstone of a different age might be colored bright orange. -A map key is always included on a geologic map?

Geologic Map 9

Chapter 1, Lesson 2, Topographic and Geologic Maps 10 *What is a contact? * A contact is a place where two rock formations occur next to each other. *There are two types: *Depositional contacts occur between rocks that formed when sediments were deposited on other sediments. *Fault contacts occur when one rock formation that is next to another has been moved.

Chapter 1, Lesson 2, Topographic and Geologic Maps 11 Depositional contact

Chapter 1, Lesson 2, Topographic and Geologic Maps 12 -How do geologists draw maps of what is underground? *Summary: -Geologists study where rocks are exposed and they sometimes drill deep into the ground and receive samples of rock. *Topographic maps show changes in elevation and surface features, along with improvements in roads and buildings. *Geologic maps show the distribution of surface rock formations. *Together they provide a complete picture of the geology of a particular area.