Category Science

A map must be as easy to read as possible, which means that symbols and colours can often give more information than words. A key explains what the symbols and colours mean. A map key or legend is included with a map to unlock it. It gives you the information needed for the map to make sense. Maps often use symbols or colors to represent things, and the map key explains what they mean. Map keys are often boxes in the corner of the map, and the information they give you is essential to understanding the map. Symbols in the key might be pictures or icons that represent different things on the map. Sometimes the map might by colored or shaded, and the key explains what the colors and shades mean. The picture here shows an example of a map key for a typical road map.

Sometimes called a legend, a map key is a table that explains what the symbols on a map mean. This helps the person reading the map understand where to find certain items. For example, a map of a mall may have symbols that reveal bathrooms, places to eat, elevators and guest services areas. A map of a city may have symbols for roads, parks, tourist attractions and public transportation stations.

While the person who creates the map can determine which symbols to use, there are some symbols that are universal. For example, a long blue line often indicates a river, while black lines represent roads. A black dot represents a city, while a star is a capital city. Green spaces often represent parks or forests. Airplanes represent airports, and a red cross is a hospital.

Represented by different colors and shapes, map symbols are used to indicate certain terrain features or important locations in a specified area. The reduced representation of a map is rendered useless without the symbols displayed in its key.

Map symbols represent the physical features of land and help the map’s reader gain an acute awareness of his surroundings. Chemeketa Community College faculty affirm that the most common map symbols include contour lines, buildings, water features, and forests and clearings. Contour lines are indicators of elevation and are usually brown. Each contour line has a number beside it that indicates “feet above sea level”. Buildings, and all other man-made features, are black and have different shapes for inhabited and uninhabited buildings. The color blue easily distinguishes water features, such as streams or lakes. Forests are indicated by the color green. The density of the tree cover depends on the shade of green. Clearings are shown as white, curvy blotches surrounded by green. Faculty at the University of Wisconsin adds map symbols such as two pickaxes forming an “x”. This indicates a quarry or a mine. Waterfalls are also shown and mark small waterways with a notch, while large rivers are marked with ripples.

Gerhard Kremer (1512-94) was called Gerardus Mercator, meaning merchant, because he made maps for merchants travelling from country to country. In 1569, he made a world map using a projection that has come to be known as Mercator’s projection. It is a map that seems familiar to us, but in fact it makes countries at the far north and south of the globe appears much larger than they really are.

A Flemish cartographer who invented a system of setting lines of latitude and longitude on charts of the spherical earth, the “Mercator projection,” which has become a standard for maps into modern times. Born in Rupelmonde, a small town in Flanders, he studied at the University of Louvain, where he achieved a master’s degree in 1532. Troubled by the conflict of ancient Greek philosophy with Christian doctrine, Mercator studied mathematics, philosophy, geography and astronomy in order to reach some conclusions about the origins and true nature of the world. He was above all fascinated by the developing art of mapmaking, which in his day benefited from the discoveries of explorers and traveling merchants. He became a skilled maker of globes and instruments; under the training of Gemma Frisius and Gaspar Myrica, two men expert in the craft, he also mastered the difficult art of engraving. A workshop set up by the three men turned Louvain into an important center of globe making, cartography, and the production of sextants, telescopes, and other scientific instruments. His far-ranging exploration and questioning of accepted Christian doctrines, however, landed him in trouble with the religious authorities, and in 1544 he was arrested, tried, convicted, and briefly imprisoned on a charge of heresy.

In 1552 Mercator moved to Duisburg, in the Germany duchy of Cleves, where he was appointed a professor of mathematics and also became a land surveyor. In Duisburg, where he remained for the rest of his life, he helped to found a grammar school and continued his work in cartography. After publishing a map of Europe in 1554 and then several other local maps of Britain and the European continent, his reputation spread. He also developed a new method of producing globes, in which he pasted on the sphere printed maps that were cut to fit by tapering their edges toward the top and bottom.

Mercator was appointed by the Duke of Cleves as an official court cartographer. He perfected his system of marking parallel lines on a map to indicate degrees of longitude that could be applied to navigation charts and allow ship captains to more accurately follow their course at sea. He first used this system on a map of the world he completed in 1569. In the 1570s he began producing an atlas, a collection that included the maps of the ancient Greek astronomer Ptolemy as well as his own maps covering France, Germany, Italy, the Netherlands, eastern Europe, Greece, and the British Isles. This work, which he completed over the span of more than twenty years, was finally published by his son after his death.

Globes can represent the Earth in miniature, with features shown in a true relationship to each other, but they are not practical to put in your pocket for an afternoon walk. Paper maps are much easier to use, but an adjustment needs to be made in order to show a curved land surface on a flat map. The adjustment chosen is called a projection. Several different projections can be used, depending on the purpose of the map.

A map projection is a method for taking the curved surface of the earth and displaying it on something flat, like a computer screen or a piece of paper. Map makers have devised methods for taking points on the curved surface of the earth and “projecting” them onto a flat surface. These methods enable map makers to control the distortion that results from creating a flat map of the round earth.

Every map projection has some distortion. Equal area projections attempt to show regions that are the same size on the Earth the same size on the map but may distort the shape. Conformal projections favor the shape of features on the map but may distort the size.

A map is a symbolic representation of selected characteristics of a place, usually drawn on a flat surface. Maps present information about the world in a simple, visual way. They teach about the world by showing sizes and shapes of countries, locations of features, and distances between places. Maps can show distributions of things over Earth, such as settlement patterns. They can show exact locations of houses and streets in a city neighborhood.

Mapmakers, called cartographers, create maps for many different purposes. Vacationers use road maps to plot routes for their trips. Meteorologists—scientists who study weather—use weather maps to prepare forecasts. City planners decide where to put hospitals and parks with the help of maps that show land features and how the land is currently being used. Some common features of maps include scale, symbols, and grids.

A map is similar to an aerial view of the Earth. The landscape is shown as though you are looking down on it, so that the relation of one place to another is clear. But maps are much more than simply bird’s-eye views. A great deal of information about the names of places and what they are like can be given in words, numbers and symbols. Although maps are more than aerial snapshots, surveying by plane or satellite has helped mapmakers considerably. Surveying on the ground is time-consuming and may be difficult in remote places. Computer-controlled aerial surveying can give very accurate results and show overall changes in such features as vegetation and coastlines much more clearly than traditional methods.

We often see the finished product of a map folded into an issue of Canadian Geographic or posted up on a wall. But how are these data-rich works of art created?

Modern cartographer’s tools allow mapmakers to show more detail than ever before in a single map with attractive, creative elements. However, this wasn’t always so.

In the early years of Canadian Geographic, from the 1930s to the ‘50s, maps were often hand drawn with no more than some surveying data and perhaps an aerial photo or two. Colour was reserved for only a few choice maps, often those linked to an advertisement, and cartographers were rarely credited.

Now, satellite data, aerial photography and computer programs all go into making a modern Canadian Geographic map. Satellite data, also known as remote sensing data, provides a wealth of information to our cartographers, including geological characteristics of land, such the height and size of mountains, and a variety of climatic information, such as sea temperatures, weather patterns and more. Aerial photography has helped mapmakers since the 1940s and offers a visual sense of the landscape and sort of a ‘big-picture’ look at the satellite data. A variety of computer programs organize the data, help plot the data and shape a landscape as well as aid in the design process.

Although there are enormous reserves of iron and aluminium in the Earth’s crust, other metals, such as tin, lead, silver, zinc, mercury and platinum are not so plentiful. Some further sources of such metals are known, but at present it would prove too expensive to reach them. As with other non-renewable resources, it is important that we recycle metals or use other materials where possible.

Minerals make up most of what we use to build, manufacture and stand on — including rocks and soil — so if we really ran out of minerals, we’d all be scrambling for a spot on the planet’s shrunken surface areas.

But if you were worried about running out of a single mineral important for industry, then you probably can breathe easy. Most of the minerals we use a lot are very abundant. Iron, for example, makes up about 32 percent of Earth’s crust, so you’d have to worry about finding a place to stand long before worrying about whether we can keep making steel.

But if we were to run out of a mineral — as in, exhaust our supply — it probably wouldn’t be because there’s none of it left on Earth. The problem would be that the processes used to extract it have become too expensive, difficult or harmful to make mining worthwhile. Even then, as mining technology advances, previously inaccessible minerals will become available and lower-producing ores will be processed more efficiently.

But still, what are we working with here? What are minerals? How big is our planet’s supply?

Minerals are substances formed naturally underground — think coal, quartz, salt. Like everything else, they’re made of elements, basic substances that can’t be broken down into simpler substances. Some minerals are single elements, like gold. When we’re assessing amounts of minerals in the world, it’s more complicated than there being a finite amount of resources that we’re using up over time. World mineral reserves are constantly revised based on estimated consumption and current production abilities. For example, in 1950, the estimated copper reserves totaled 100 million metric tons. Over the next 50 years, world copper producers extracted 339 million tons — by 1950 standards we should have run out of copper three times over. For most minerals, supplies have actually increased during the 20th century even though we’re using them up faster than ever.

So it’s unlikely that Earth will ever run out of minerals. But will people ever experience mineral shortages?

In a sense we’re always facing mineral shortages. Shortfalls and reduced production stimulate new mines, new technological innovations and lower standards for what counts as high-quality ore. We’re also using a wider array of minerals. More than 60 different elements can be used to build a single computer chip. A lot of these are minerals that never had industrial applications until 20 or 30 years ago, and they’re produced in such small quantities that they’re much more susceptible to supply risks.