BASICS OF GEOLOGIC MAPPINGWhat are geologic maps and why are they important?A geologic map shows mappable rock units, mappable sediment units that cover up the rocks, and geologic structures such as faults and folds.. Mappable units are shown as different colors or patterns on a base map of the geographic area.Geologic maps are important for two reasons. First, as geologists make geologic maps and related explanations and cross-sections, they develop a theoretical understanding of the geology and geologic history of a given area.Second, geologic maps are essential tools for practical applications such as zoning, civil engineering, and hazard assessment. Geologic maps are also vital in finding and developing geological resources, such as gravel to help build the road you drive on, oil to power the car you travel in, or aluminum to build the more fuel-efficient engine in your next vehicle. Another resource that is developed on the basis of geologic maps is groundwater, which many cities, farms, and factories rely on for the water they use.Essential Components of Geologic MapsA complete geologic map has at least two features: (1) the map itself, and (2) the map legend or key that explains all the symbols on the map. Professional geologic maps usually have two other components as well: (3) an accompanying explanation of the rock or sediment units, and (4) geologic cross-sections of the map area.The legend or key to a geologic map is usually printed on the same page as the map and follows a customary format. The symbol for each rock or sediment unit is shown in a box next to its name and brief description. These symbols are stacked in age sequence from oldest at the bottom to youngest at the top. The geologic era, or period, or epoch--the geologic age--is listed for each rock unit in the key. By stacking the units in age sequence from youngest at the top to oldest at the bottom, and identifying which interval of geologic time each unit belongs to, the map reader can quickly see the age of each rock or sediment unit. The map key also contains a listing and explanation of the symbols shown on the map, such as the symbols for different types offaultsandfolds.The explanations of rock units are often given in a separate pamphlet that accompanies the map. The explanations include descriptions with enough detail for any geologist to be able to recognize the units and learn how their ages were determined.If included, cross-sections are usually printed on the same page as the geologic map. They are important accompaniments to geologic maps, especially if the map focuses on the geology of the bedrock underneath the soil and loose sediments.

A map like this might be presented to you at the competition. Make sure you understand that different colors represent different rocks from different time periods, and you should be able to easily determine the age of a certain rock or sediment given the geologic time scale in the maps key.

Geologic Cross-SectionsA geologic cross-section is a sideways view of a slice of the earth. It shows how the different types of rock are layered or otherwise configured, and it portrays geologic structures beneath the earth's surface, such as faults and folds. Geologic cross-sections are constructed on the basis of the geology mapped at the surface combined with an understanding of rocks in terms of physical behavior and three-dimensional structures.

Topographic Map BasicsA topographic map, simply put, is a two-dimensional representation of a portion of the three-dimensional surface of the earth. Topography is the shape of the land surface, and topographic maps exist to represent the land surface. Topographic maps are tools used in geologic studies because they show the configuration of the earths surface. Cartographers solve the problem of representing the three-dimensional land surface on a flat piece of paper by using contour lines, thus horizontal distances and vertical elevations can both be measured from a topographic map.The following are general characteristics of contour lines:1. Contour lines do not cross each other, divide or split.2. Closely spaced contour lines represent steep slopes, conversely, contour lines that are spaced far apart represent gentle slopes.3. Contour lines trend up valleys and form a "V" or a "U" where they cross a stream.

Latitude vs Longitude

The latitude specifies a location's distance north or south of the equator. The longitude specifies the location's distance east or west from an imaginary line connecting the North and South Poles, called thePrime Meridian.

Map ProjectionsMercator (distorts the size and shape of large objects; scale increases from Equator to the poles- where it becomes infinite; meridians and parallels of latitude cross at right angles)

Robinson (Compromise- distorts size and shape; shows whole world at once)

Universal Transverse Mercator Coordinate System (UTM)- not a singlemap projection. The system instead divides the Earth into sixty zones, each a six-degree band of longitude, and uses asecanttransverse Mercator projectionin each zone.