MAPS Introduction Accurate maps of the Earth’s surface are vital for learning about geologic processes and how geologic processes interrelate with other global phenomena such as climate, ocean processes, biologic activity and the impact of human activity. In the past, maps were made through detailed surveying techniques and hand drawn. With the development of airborne and now satellite surveying the production of maps is much less time consuming and tedious. The advent of high-speed computers, easy to use software and digital data has also greatly changed the nature of maps and map making. Geologists use many types of maps depending on the type of data available and the nature of the geologic problem to be addressed. In this section we present information on topographic maps, geologic maps and a brief description of geologic information survey (GIS) and how it applies to maps. Topographic Maps Topographic maps are a two dimensional representation of Earth’s three-dimensional surface and are a basic tool for many geologic endeavors. The shape of the Earth’s surface is called topography. The heights of Earth’s surface features are compared to the average height of the oceans (called sea level) around the globe. The height above sea level is referred to as elevation. Lines of equal elevation are called contours. Topographic maps of the ocean floor have also been constructed, most recently using variations in mean sea level (link). There are many links that have information and examples of topographic maps including spectacular topographic maps of the ocean floor. There are also numerous links for activities involving topographic maps. Topographic Map Links:      topographic maps available online           http://www.topozone.com/      topographic map symbols (USGS)           http://mac.usgs.gov/mac/isb/pubs/booklets/symbols/ Geologic Maps The basis for understanding the geology of an area is the geologic map. Using a topographic map as a base, a geologist records information onto the map such as outcrop location, rock type and type of structure observed at the outcrop. After covering the area of interest, a geologist will compile the information on a final map and apply a set standard of colors for different rock types and symbols for different structures. The final product is a detailed, colored two-dimensional representation of the distribution of rock types found in the area. A geologic cross section is a vertical slice through a part of a geologic map and can be constructed from the geologic map. Both the geologic map and cross section are used to help piece together the geologic history of an area. Geologic maps come at a variety of scales; from statewide to those covering a single topographic map. Geologic maps of the continents and even the globe are also available! The detail on maps is dependent on the scale; for maps of the globe only the very basic aspects of the geology can be represented whereas smaller scale geologic map carry much greater detail including the location of different rocks type and individual folds or faults. Details on geologic maps can be found at the following web sites: