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Date: 01-01-94 (15:49) Number: 2509 Message 9 of 11 From: Tom De Luca Refer#: 0 To: DAVID CHESSLER Recvd: No (PVT) Subj: Map & Compass Ver 4.0 Conf: 11 Private Email ------------------------------------------------------------------------------ ***************************** * * * EMPLOYING MAP AND COMPASS * * Ver. 4.0 * * * ***************************
********************************* * By Tom DeLuca, Pack 400 * * All Rights Reserved 1993 * * Created For Non-Profit - * * BSA Classroom Use Only * *********************************
"When you have worn out your shoes, the strength of the shoe leather will have passed into the fiber of your body. I measure your health by the number of shoes, hats, and clothes you have worn out. He is the richest man who pays the largest debt to his shoemaker..." Ralph Waldo Emerson
The purpose of this training: As a result of this course, each participant should be able to determine their own ground location on a Map, and demonstrate Map & Compass techniques.
Needed supplies: Topographical Map of area, Needle Map Compass, Paper, Pencil, and Scientific Calculator.
INTRODUCTION Everybody who goes out into a wilderness area, especially if they have never been there before, whether just simply fishing, boating, hiking for the day, or actually camping, needs to carry on their person:
Water Small First Aid Kit (Snake Bite Kit) Sun-Screen (Sunglasses) Whistle Pocket Knife Waterproof Matches Space Blanket
and a Map & Compass.
When traveling in wilderness that you have never seen before, a map, without knowing where north is... is just about worthless. How are we going to orient our maps in low visibility rain or fog without a compass? (There are however many Boy Scout ways of finding north as we will see...)
On the other side of the coin, a Compass, all by itself, without a Map, is also totally useless. Sure, we can find north, but what good is that information, if we have no specific destination, or landmark to aim for? Just walking north may send you deeper into the woods. While your are lost, you could use the compass to scout around the area safely. However, if you do not even have a "map" in the mind, the simple idea where you're going, the knowledge of north is not going to be much good.
A Map & Compass work together to form a single Vital Tool, for guiding anyone through the backcountry, through any situation, or weather condition.
The trained Men and Women of our Mountain Search & Rescue Teams are the ones called in from their regular jobs and volunteer to find lost victims. They say that the rescues of literally thousands of hikers, campers, and hunters, which lose their way in our National Wilderness areas every year, could have been avoided if these people had only used a map and compass. They say that many of the people that do carry them, don't even know how to use them properly. A great number of these lost people end up being experienced Outdoorsmen who were to involved with looking around, and just forgot to pay attention to where they were.
In our country, the funds used to mount a rescue operation, is so large, that some counties are just not equipped to meet the financial drain.
In parts of the have been made to pay for their own air-ground search operations.
So far in our local a search operation is charged back to the county to which the lost person lives.
Maps are a highly reduced written representation of the ground as seen from the air. They magically allow us to transport a small portion of the world around in our pockets. With all a map's pretty colors, lines, and patterns, it's important to remember that there isn't a single dot, dash, or line drawn on it just to make it more appealing to the eye. Even the single dash/space in the twisting line of a foot trail represents 120 feet.
Take your time. They take some careful field observation, thought, and study, to see all the information they present. Look at as many different maps of the area that you can get your hands on... before you step one foot into wilderness. By the time you find yourself "lost," it maybe already too late to use your map & compass. Fear can set in, and hamper your ability to think properly. At all times, without exception, plot your course, and fix your position with a pencil. Even if you are traveling with very experienced people, don't just blindly follow where they lead. They can become dehydrated, injured, or turned around, and maybe just have not discovered it yet. It may be left up to you to come up with a plan of action. With the solid understand of map & compass given in this course, and a little back country common sense, navigating through any unfamiliar area should hold no problems for you.
************ * MAPS * ************
"Cartography," is the modern science of making maps & charts. The actual name "Chart," comes from the Greek word "Chartos," meaning "Leaf or Sheet of Paper," and is usually a map that is used by sailors, aviators, and astronomers. The name "Map," comes from the Latin word "Mappa," meaning "Napkin or Cloth," and usually refers to a chart of the land.
TYPES OF MAPS. `Atlas' are a collection of Maps bound into a book. `City Maps' are called `Planimetric Maps' showing roads and freeways. `Land Use Maps' are used in agriculture and soil conservation. `Cadastral Surveys' define boundaries of tracts of land for real estate ownership and tax purposes. `Soil Maps' are Aerial Maps used for planning highways. `Population Maps' show where people are concentrated. `Rainfall Maps' show the annual precipitation. `Globes' show a planet as a whole in a way that a Map can not. `Relief Maps' have bumps at the higher elevations. `Political Maps' show different colors for various countries. `Forest Service Maps' show basic features, mountains, stream names, and jeep roads but are without contour lines. `Weather Maps' appear in the daily news paper. `Wind Charts' show the prevailing wind currents and their names. `Nautical Charts' show the depth of the ocean floor. `Aeronautical Charts' are used by aviators. `Star Charts' show nebulae and constellation locations. `Mineral Maps' show the kinds of ore in the ground. `Topographic Maps' show the relief of the landscape as lines.
Just to name a few.
Many maps are dual purpose, as they are overlaid with several types of Map information.
Every Pilot, Sea Captain, or wilderness Backpacker, starts and ends their trek by first defining a course, no matter what method of route finding is used during the trip. Plotting a course in route, always involves dealing with what is presently around you here and now, as well as what is to be coming up in the both the near, and distant future. The outdoor enthuest must at all times, know his position by checking his map & compass frequently. He also needs to be aware of alternate routes, should danger hamper his progress.
It is to your own best interests, and for the good of mankind as a whole, that you come to be comfortable with the world of maps & compass.
TOPOGRAPHIC MAPS. The Greeks did much in helping to develop the field of geography, and the derived word "Topographic," comes from a combination of 2 Greek words. "Topos," meaning, "Place," and "Graphin," meaning to "Write or Draw." Topographic maps, developed by the United States Department of the Interior Geologic Survey Team (USGS), are what backpackers use most in wilderness travel. This type of map can give the trained eye a very good idea of the lay of the land.
The skills of reading a map, begin with first finding the correct map. The TITLE or name of a map is found in the upper-right, and lower-right corners of a Topo Map. It will be named after the most clearly visible location within it's boundaries. It could be named after a mountain, a town, or even a lake, ect... When the map is folded for storage, this name should be allowed to face out.
The DATE the map was made, is located in the lower-right corner, and it references how far back the map was actually drawn, or at least updated. It is very important to take note of it, because many maps being sold today have not been updated now for over 50 years. This means all the newer changes in the landscape will not have been printed on them. However you can bet that the map was probably correct when it was first surveyed. Examples of some kinds of changes to watch for include:
Completely new trails & new forks in old ones. Newly built man made features, and the removal of old ones. A swamp may have been drained, or deepened into a lake. Lakes can silt up into marsh. Streams can dry up, or be diverted. A dirt road may have been made into a highway. A forest fire may have ravaged the area, and foliage hasn't grown back yet.
So be aware of the revision dates on maps. PURPLE DATES and FEATURES mean that new information, gathered by aircraft or satellite photographs, have been added to the map, but that it has not been re-surveyed in the field yet.
MAP SCALE. Since the 1920's, it has been a practice to subdivide a 360 degree globe, into Degrees, Minutes, and Seconds of Arc. Each Degree is broken down into 60 Minutes, and each Minute is broken down into 60 Seconds, just like a 24 hour clock. A 7-1/2 Minute Map (or 7'30"), covers 7.5/60ths of 1 Degree of land area on the real globe.
A 15 Minute Map covers 15/60ths of 1 Degree of area on the globe. A Four times larger area than the 7'30" maps.
As the Earth turns, it will take the Sun just 7 and a half minutes, or 15 minutes, to sweep over the area covered by these maps.
LONGITUDE,
(North/South lines), is also
called " starts at 0 degs (The Prime Meridian) at The Greenwich (pronounced "Grennitch") Royal
Observatory, near and counts up as it increments west. On the left side of the Map, a typical west longitude on a 7-1/2 Minute Map might read 117 deg 37'30" (read 117 Degrees, 37 Minutes, and 30 Seconds), and on the right, 117 Deg 30'. So by example...
117Degs 37' 30" - 117Degs 30' 00" ------------------ 0 Degs 7' 30"
That equals 7-1/2 Minutes across.
LATITUDE, (East/West lines), also called "Parallels," starts at 0 Degs at the equator, and becomes 90 degrees at the poles. This means there is only 180 individual degrees from South to North. However, looking at a silhouette of the planet, you would see there is actually 360 degrees in this direction also.
The typical 7-1/2 Minute Map might read 34 Deg 22'30" at the top, and 34 Deg 15' at the bottom. So by example...
34Degs 22' 30" - 34Degs 15' 00" ----------------- 0 Degs 7' 30"
That's also 7-1/2 Minutes.
So the area covered by a 7-1/2 Minute Map is really 7-1/2 Minutes North Latitude by 7-1/2 Minutes West Longitude. (About 8x8 miles.)
By the same token, the area covered by a 15 Minute Map is really 15 Minutes North Latitude by 15 Minutes West Longitude. (About 16x16 miles.) This is simply what the Maps are called, and how they arrived at that distinction.
If you look at
Topo Maps of the called "Quads" for short, you will notice that the Maps are not perfectly rectangular. In the Northern Hemisphere they are wider at the bottom than they are at the top... Get a ruler out and measure it... Hmmm... Let's see, 7-1/2 Minutes Latitude by 7-1/2 Minutes Longitude... Sounds like a perfect square... So why AREN'T they square? Well these Maps are not simply Maps of a region like a Car Map is. These are actually "Area Maps" that show a "Quadrangle of land" as based on USGS Land Surveys, which are in turn based on Latitude & Longitude lines. They are called "Polyconic Projections," meaning that they are drawn to have every parallel line (Latitude) equal to those distances on the globe, sort of what you would really see looking down from space. The Longitude lines as they near the poles, get closer together, and you would expect a "Polyconic" Map to also reflect this. A Map of the equator region will be nearly a perfect square. But at Latitudes above 45 Degs, Topo Maps grow taller and narrower. Maps of the
far northern edges of triangular in shape. The 1:24,000 Scale series Topo Maps will cover 68 square miles in southern miles along the Canadian Border.
In more than 50% of down into RANGES, TOWNSHIPS, and SECTIONS, as is seen on all western QUADRANGLE Maps produced by the USGS. This information is also conveniently found on western FOREST SERVICE MAPS, and we will be covering this aspect further in a moment.
The SCALE of a map is also explained as a ratio between the distances on the map, as compared to the real distances on the landscape. It is expressed on a Topo Map as a fraction such as 1:1,000,000 which means that 1 UNIT of distance on the Map, equals 1,000,000 UNITS on the earth. If, for example, 1 inch on the map, equals 1,000,000 inches on the landscape, the 1 inch would equal about 15.7 miles of landscape.
The most useful maps for wilderness travel are by far the 7-1/2 Minute USGS Topo Maps, as the 15 minute maps are being phased out. The 15 Minute Map covers almost four times more area than a 7-1/2 Minute Map does. But the 7-1/2 Minute Map shows much greater detail in the landscape.
A 7.5 Minute Map is said to have a "larger scale" because it has a ratio closer to 1:1. Features of the land on the 7.5 Minute Map (1:24,000), look bigger, than they do on a 15 Minute Map (1:62,000). Small scale maps cover larger areas. A globe is a "small scale" map.
Distances on most maps are also represented by a BAR SCALE. It is found at the bottom-middle of the Topo Map, or in the "Legends" of most other maps. It can convert inches to miles, feet, and kilometers, and the map can be easily Xeroxed, educed or blown up, with out any loss of scale.
A 15 Minute Map typically has a scale of 1:62,500, meaning 1 inch equals about 1 mile (5280 feet * 12 inches = 63,360 inches in a mile). The Map covers 14.5x17 miles (not square is it?), and the "Contour Intervals" are 50 feet apart.
A 7.5 Minute Map typically has a scale of 1:24,000, where 1 inch equals about 2,000 feet (.378 miles). The Map covers 7x8.5 miles, and the "Contour Intervals" are 40 feet apart.
Other common USGS Map Scales Include...
7.5 Minute Maps have a Scale of 1:24,000, where 1 inch = 2,000 feet, and covers 49 sq. mi. along the 48 parallel, and 71 sq. mi. in
7.5x15 Minute Maps have a Scale of 1:25,000, where 1 inch = 2083 feet, and covers 100 to 140 sq. mi.
15 Minute Maps have a Scale of 1:62,500, where 1 inch = 1 mile, and covers 197 to 282 sq. mi.
30x60 Minute Maps have a Scale of 1:100,000, where 1 inch = 1.6 miles, and covers 1578 to 2167 sq. mi.
1x2 Degree Maps have a Scale of 1:250,000, where 1 inch = 4 miles, and covers 4580 to 8669 sq. mi.
Around the border of the Topo Map, you will find 8 NAMES OF OTHER MAPS. These are the names of other Topo Maps that match up, and belong next to this current Map. If your trail dips off the map momentarily, and returns to the map, be sure to pick up the neighboring map also. The little off map hike may twist unexpectedly and take you miles out of your way. You may not know this until it's too late, when the sun is setting.
GRID LINES. Look around the edge of the Topo Map for blue numbered indexes, or TICK MARKS. These are accompanied with numbers like 3801, or 445, having 2 different sized characters representing the same number. They are spaced at a distance of 1 Kilometer apart, and are also called "Klicks," short for Kilometers.
This Grid System is borrowed from another type of map called the 1,000-Meter Universal Transverse Mercator Map, or UTM Grid for short. You will find this reference in the lower-left corner of the Topo. A "Mercator Projection" was named after Gerhardus Mercator (Juh-rahr'-duhs Mur-kay'-tur, 1512-1594), a Flemish Cartographer, who first developed it in 1569. It is the flat map of the world, found in every school class room, which badly distorts still used on just about every modern boat and aircraft that crosses the pacific and Atlantic oceans. Back in the days of Marco Polo, Magellen, Columbus, and Sir Francis Drake, it was the only map they had. It is by far the most widely used Nautical Chart of all time. The Military is now using the Mercator Grid System as it's Standard Coordinate System, and since it is already printed on our maps through out the world, it provides us Another way to locate exact points on the map. The calculation of Latitude & Longitude into Degrees, Minutes, and Seconds, is much harder to do than using the UTM Grid, and this method has become very
popular in Rescue
Teams here in the being a "Land Management" organization, still uses the Quadrangle coordinate system however.
GRID COORDINATES are places where the Horizontal and Vertical Grid lines cross.
Between each Tick Mark, each Kilometer is subdivided into 10 more subsections, having 100 meters each. So a "Grid coordinate" number will have the main coordinate, of say 57 kilometers from a Latitude or Longitude line, and will also state the number of 10th's within that kilometer. Say 57.3 for example, so your coordinate would be 573. If you get within 100 meters from someone on the ground, you're close enough to yell for them.
Look for the "Hard Corner" of your 7.5 Topo map. This is the corner where both the latitude and longitude lines are marked as ending in 30" seconds. This would be the center of a 15 minute map of the same area. There is only one Hard Corner per 7.5 minute map. It can be 1 of any of the four, depending on the map section you have. It is an important corner. There you will see that the Grid Tick Marks are really way up in the thousands. The map will read 466000meters E longitude x 3775000meters N latitude, and they indicate the number of Meters from a major map are used for giving Grid Coordinates, and the smaller numbers are left out completely, so the NAME of the correct map becomes part of the coordinate also.
A typical Grid Coordinate location would look like...
Meaning the location
is on the Longitude Grid Tick 32 & 6/10ths Kilometers by North Latitude Grid Tick 30 & 1/10ths Kilometers. The order of the 2 numbers is always "Along the corridor and up (or down) the stairs," (Long then Lat).
The DECLINATION CHART is located at the bottom of the Topo Map. It shows the different angles between TRUE NORTH, MAGNETIC NORTH, and GRID NORTH. In map making, it is standard to place True North at the top of the Map. But don't assume this. Look on the map, as there will be an arrow to point to north. Grid North as an example, is not exactly a MERIDIAN LINE, meaning that it does not exactly point to the North Pole. It's deviation from True North will always be shown on the Declination Chart. This chart is a very important part of the Map for anyone using a Map & Compass. You will be getting to know it very well.
TRUE NORTH is a directional line between any position on earth, to the True North Pole. All lines of Longitude are True North lines, and are also called `Meridian Lines.' True North is usually symbolized by an ARROW WITH A STAR on a Topo Map.
MAGNETIC NORTH is the direction to the Magnetic North Pole. It is actually the southern pole of the earth's central magnet, as is shown by the north seeking needle of a Compass. (Like magnetic poles repel, while unlike poles attract.) Magnetic North is usually symbolized be HALF AN ARROWHEAD on a Topo Map.
GRID NORTH is the north that was established by the vertical grid lines during the Map making process. Grid north is usually symbolized by the letters GN or the letter Y on a Topo Map.
CONTOUR LINES on a Topo Map are brown. They join all heights of the same altitude together. The difference between 1 contour line and the next is called the CONTOUR INTERVAL, and this value is located at the bottom-center of the Topo Map, under the BAR SCALE.
Every 5th Contour Line is a darker brown line called the INDEX CONTOUR, and it has the elevation printed on it. Each Contour Interval may equal 200 (or 250) feet between dark lines.
In addition, there are brown DASHED CONTOUR LINES in placed between the normal Contour Lines in very flat areas. These are called CARRYING CONTOUR LINES, and they represent elevations between very widely spaced Contour Lines. For example, in a Desert area where the land may gain or lose 50 feet in a mile, and the Contour Interval of the map were 40 feet, the Carrying Contour Lines would represent 20 foot indexing.
When Contour lines are widely spaced, you can expect to find a gentle slope. When they are bunched really close together, you can expect there to be a cliff. As contour lines cross a riverbed they look like a "V" shape pointing up stream. When they go around the spur of a mountain they look more "U" shaped and point down the hill. Map reading is skill you'll have to develop. Only by practicing it, will you be able to see the shape of the landscape, in your minds eye.
TRIGONOMETRIC SURVEY POINTS, or STATIONS, are very accurately surveyed places, marked on the Map. They can help give a map reader an accurate idea of the land's actual relief. There are "Vertical Controls," and "Horizontal Controls."
A permanent "Bench Mark" (BM), is a small 6X6 inch concrete pillar with a brass USGS disk marker called a "tablet," physically placed in the ground, usually at mountain summits, but also in the flat areas around the city. These are called Monuments or Stations. On the BM's face is inscribed the exact elevation above sea level, and the latitude and longitude of the marker. They can be a Vertical Control, a Horizontal Control, or both.
These BM Monuments are used as the corners of much larger triangles. The Geological Survey Department them for calculating altitudes and distances around the local area, using angular measurement (Trigonometry & Geometry), for the exact placement of buildings and bridges, to follow design engineering diagrams.
There are many kinds of surveys. Surveys of water are called Hydrographic Surveys. Surveys for roads or pipelines are Route Surveys. Surveys of the land for property lines are Cadastral Surveys. Surveys that set the wooden steaks in the ground at a construction sites are Construction Surveys used in building bridges, mining tunnels, and buildings, don't remove them from a construction site.
VERTICAL CONTROLS, can be found anywhere, in walls, gate posts, sides of buildings, sides of trees. They show the height above average sea level which has been figured out very accurately. Permeant BM Monuments are marked on the map as "BM x with elevation." Recoverable markers (typically red plastic surveyors tape nailed in place) are marked on the map as "x with elevation."
HORIZONTAL CONTROLS, usually appear only on maps along roads, near sea level, and in deserts, to better aid the map reader on very large flat areas of land, where the contour lines are naturally widely spaced. They can be monuments, recoverable, or not marked on the ground at all. They are however always marked on the map with an "Triangle with elevation," or "BM Triangle with elevation" for permeant Monument markers.
QUADRANGLE markings, also called "Cadastral (ke-das'-tral) Coordinates" or "Legal Descriptions," show up across the face of the Topo Map as very light red lines and numbers. The squares are in groups of 36 blocks, called Townships, and are repeated over and over again across the face of the map, and is super imposed over the map's regular Contour Line data. These are PUBLIC LAND SURVEY (USPLS) area measurements, and are public records used to record the value, extent, and ownership of land, as a basis for taxation. The location of your map's QUADRANGLE within the state, is located at the bottom of the Topo Map.
In 1785, the system called the "Land Ordinance" was created. Thomas orderly way to transfer blocks of homestead land to the settlers, without leaving unused slivers of land left over.
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