There are different types of maps for different purposes. When you need directions to a new place, a road map is what you use. But let's imagine you're out hiking and have gone off the road. In that case, you need to know more about the land you're in. That's when a topographic map comes in handy.

How is a topographic map different from a regular map? Basically, topographic maps show a 3-D surface. However, they appear on a two-dimensional surface. These maps show the land's shape. You can see its mountains, valleys, bodies of water and more. 

The U.S. Geological Survey (USGS) produced its first topographic map in 1879. It still makes them today. They were once made by hand. However, photography has developed since then. The maps are much more exact. They are easier to produce. 

Contour lines are the key to interpreting topographical maps. They appear as curved or straight lines, and each line represents a specific elevation above sea level. Let's look at some important aspects of contour lines:

• Contour Interval: The contour interval is the vertical distance between adjacent contour lines on a map. It tells us how much the elevation changes between two lines. For example, if the contour interval is 20 feet, every contour line represents an increase or decrease of 20 feet in elevation.

• Close Contour Lines: When contour lines are closely spaced, it indicates steep terrain. The closer the lines, the steeper the slope. This is helpful when planning hikes or understanding mountainous regions.

• Farther Apart Contour Lines: When contour lines are farther apart, it suggests flatter or gently sloping areas. This can represent plains, valleys, or plateaus.

When looking at a topographical map, there are key features that can help us understand the land better. One important feature is mountains and hills. On the map, mountains are shown with closely spaced lines forming circles. The center of these circles represents the highest point, called the summit. Hills, on the other hand, are shown with contour lines forming circular shapes that get larger as you move away from the center. Another feature to look for is bodies of water. Lakes, rivers, and streams are often shown in blue on the map. They can help us navigate and understand how water flows through the area. By identifying these key features, we can get a clearer picture of the land and have more exciting adventures! 

Here are some essential elements to look for:

• Mountains and Hills:
  Mountainous regions are indicated by closely spaced contour lines forming concentric circles. The center of these circles represents the peak or summit of the mountain. Hills are identified by circular contour lines with decreasing elevations as you move outward.
  
  

• Valleys and Depressions:
  Valleys are represented by contour lines forming a "V" shape. The "V" points upstream, showing the direction of the water flow. Depressions, such as basins or sinkholes, are illustrated by contour lines forming concentric circles with decreasing elevations as you move inward.
  
  

• Bodies of Water:
  Lakes, rivers, and streams are depicted on topographical maps using blue lines or shading. Blue lines show the course of rivers, while lakes and ponds are depicted as blue areas. These water features give important context to the map and help with navigation.

When you look at a topographical map, you'll often find a legend or key that explains the symbols and colors used on the map. The legend helps us understand the different features represented on the map. For example, contour lines are usually shown in brown, and they indicate changes in elevation. The closer the lines are, the steeper the slope. You might also see blue lines or shading, which represent bodies of water like lakes and rivers. The legend will tell you what each symbol and color means, so make sure to refer to it when exploring the map. It's like a secret code that helps us decipher the information and navigate our way through the exciting world of topography!

Another important element you'll find on a topographical map is the scale. The scale helps us understand the relationship between the distance on the map and the actual distance on the ground. It tells us how much smaller the map is compared to the real world.

Obviously, maps aren't life-sized. Otherwise, they would not fit in our backpacks. Instead, cartographers plot maps on a ratio scale. With those, one measurement on the map equals another larger amount in the real world. The first number of the scale is always 1. It's your unit of measurement. Usually, it is an inch. The second number is the ground distance. For example, say your USGS map has a scale of 1:24,000. That means that 1 inch on the map is equal to 24,000 inches (2000 feet) in the real world. Your map's scale legend will always be at the bottom. For USGS topographic maps, 1:24,000 is the scale most often used. Some maps are based on metric units. Such maps use a scale of 1:25,000. With that, 1 centimeter equals 0.25 kilometers. You'll find most of the United States mapped at the 1:24,000 scale. Only a few are not. Puerto Rico is one. It maps at 1:20,000 or 1:30,000. It is because the country was originally mapped at a metric scale. Few states map at 1:25,000. Most of Alaska maps at 1:63,360. Its great size is the reason. 

You can plan an entire hiking trip using a topographic map. By doing so, you will avoid unhappy surprises. The map can tell you very much. It will tell details about an area's elevation. You can also see the best way to climb a peak. Landmarks on the map can tell you where you are.

It's always best to plan your hike in advance. First, select the area in which you and your friends will be walking. Then, get yourself a topographic map. The USGS, for example, offers them online. Trails appear on a topographic map as thin black lines. Roads will be thicker red or black lines. As you choose your route, closely watch your map's contour lines. If the lines are far apart, any changes in elevation will be slow and gradual. If they're close together, though, you'll have a steep hike ahead of you. The highest point of your climb appears as a circle in the center of the lines. It's sort of like the rings on a tree.

Does a climb looks too steep? If so you can use the map to plan an easier route. It will take you around around any hills or mountains. Remember, if you follow the map's contour lines, your elevation will keep steady.

Okay, you chose the best route. Now look at the scale. It will help find out how far you'll be hiking. This way you'll know how many supplies you'll need in your backpack. Keep in mind you likely won't be hiking in a straight line, though. Experts say to mark your route on the map with a string. Make sure to include all the twists and turns. Then, translate your string distance to the map's Scale.

Your map will also show you where to find water. It too can show how to stay within the timber line. This is the altitude where trees start to disappear. That way, you'll know where to go if you need shelter. Don't forget to note the symbols on the map. That way you can be sure you're not hiking onto any private property. You can also avoid dangerous areas. A mine shaft hole would be an example.

By understanding topographical maps, we can explore and appreciate the incredible diversity of our planet's surface. From towering mountains to meandering rivers, these maps offer a wealth of knowledge about the world around us. Remember to take your time, practice reading contour lines, and use the legends to interpret the symbols. With this newfound skill, you'll be ready to embark on exciting adventures, whether it's hiking, planning a trip, or simply exploring your local area.