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A topographic map is a graphic representation of selected manmade and natural features of a part of the earth's surface plotted to a definite scale. The distinguishing characteristic of a topographic map is the portrayal of the shape and elevation of the terrain.
The conversion factors in the following tables are for conversion of our customary (English) units of measurement to SI*units, and for convenience, reciprocals are shown for converting SI units back to the English system. The first table contains rule-of-thumb figures, useful for "getting the feel" of SI units or mental estimation. The succeeding tables contain factors accurate to 3 or more significant figures. Please refer to known reference volumes for additional accuracy, as well as for factors dealing with other scientific notation involving SI units.
Topographic maps are a detailed record of a land area, giving geographic positions and elevations for both natural and man-made features. They show the shape of the land the mountains, valleys, and plains by means of brown contour lines (lines of equal elevation above sea level). In steep mountainous areas, contours are closely spaced; in flatter areas, they are far apart. The elevation of any point on the map can be estimated by referring to the elevations of the contour lines above and below it.
This booklet lists some of the many types of maps and charts available from the Federal Government-from demographic maps to foreign aeronautical charts.
The Geological Survey is a Federal research and fact-finding agency that provides for the people of the United States
The U.S. Geological Survey Library, established in 1882, is one of the largest earth science libraries in the world. The Library System consists of the headquarters library in Reston, Virginia, and three branch libraries in Denver, Colorado; Flagstaff, Arizona; and Menlo Park, California
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If a schoolboy asked this question, you would answer it easily enough. "Why, water is a liquid found in and around the earth. Water is the sea, lakes, streams, springs and what comes gushing out of the tap when we turn it on." If he still looks a little unsatisfied, you would explain that our bodies are three-fourths water, and that water covers threefourths of the earth's surface. But you would have to admit to yourself that these facts, interesting as they are, do not quite answer the boy's question: "What is water?"
Man's economic and social progress depends on a plentiful and readily available supply of water. From his earliest days, man has found water to be an essential ingredient in improving his environment and the quality of life. Increased production of goods and continued introduction of new products have been accompanied by a phenomenal increase in water use. Industry, including hydroelectric power, now uses about 3 trillion gallons a day, or about seven times the average daily discharge of the Mississippi River.
Maps are, among other things, a way of making geography visual. They are world views, ways of thinking, and ways of communicating. They depict our world and guide us through it. Visual Geography probes the essence of maps and mapmaking. It follows the story of cartography through the millennia, across the globe, and beyond the solar system. It includes some of the world's most beautiful and enduring maps, some of its most historic - a map in Columbus' hand, the map that was carried to the Moon, the first map to show America - and it examines the urge to map, to measure our world, and to record it graphically.
Within the technology of the space age lies a key to increased knowledge about the resources and environment of the Earth. This key is remote sensing detecting the nature of an object without actually touching it. Although the photographic camera is the most familiar remote-sensing device, other instrument systems, such as scanning radiometers and radar, also can produce photographs and images. On the basis of the potential of this technology, and in response to the critical need for greater knowledge of the Earth and its resources, the Department of the Interior established the Earth Resources Observation Systems (EROS) Program to gather and use remotely sensed data collected by satellite and aircraft of natural and manmade features on the Earth's surface.
A series of uniform, nationally consistent State Hydrologic Unit Maps that accurately delineate the hydrographic boundaries of major U.S. river basins has been prepared by the U.S. Geological Survey in cooperation with the U.S. Water Resources Council. These maps provide a standardized base for use by Federal and State water resources agencies throughout the country.
Space age technology contains a key to increased knowledge about the Earth's resources; this key is remote sensing detecting the nature or condition of something without actually touching it. An early and still most useful form of remote sensing is photography which records the scene, as man sees it, on film sensitive to that part of the electromagnetic spectrum called visible energy. Electromagnetic energy travels in waves of various lengths; most are invisible to the human eye. Wavelengths progressively longer than those that the eye can see are infrared and microwave. Wavelengths progressively shorter than the eye can see are ultraviolet, X-rays, and gamma rays.
What comes to your mind when you think of outdoor recreation? Boating? Camping? Hiking or backpacking? Horse-back riding? Hunting or fishing? Chances are, if you can name an outdoor activity, you can do it on public lands.
Frog malformations have been reported from 42 states. The broad geographic distribution of these malformations warrants national attention. Scientists at the USGS National Wildlife Health Center in Madison, Wisconsin are studying this problem in an effort to document its scope and to determine the causes of the observed malformations.
"Exploring Caves" is an interdisciplinary set of materials on caves for grades K-3. Caves entail at least five scientific disciplines: earth science, hydrology, mapping, biology, and anthropology. Each of these disciplines involves a unique content area as well as the development of particular intellectual skills. This unit aims at helping teachers to sort and organize the most important ideas in this rich scientific area. Detailed lesson plans serve as ways to pass these ideas on to very young students. Most American caves are big holes that form in limestone rock. The holes begin as cracks in limestone. The cracks get bigger and bigger. They grow into underground streams, rivers, and even lakes. When water drains away, the waterways turn into open cave tunnels, passages, and caverns. It takes 10,000 to 100,000 years to form a cave big enough for people to move around inside. Water drips constantly in caves. The drips dissolve limestone minerals in one part of the cave. As water dries out, the minerals build up in other places. In this way, beautiful cave rock formations and crystals grow over thousands of years. These rock formations change dark limestone caves into hidden fantasy lands.
Global change is a relatively new area of scientific study using research from many disciplines to determine how Earth systems change, and to assess the influence of human activity on these changes. This teaching packet consists of a poster and three activity sheets. In teaching these activities four themes are important: time, change, cycles, and Earth as home.