MICHIGAN FORESTS FOREVER TEACHERS GUIDE
Introduction
Using maps and compasses have many applications in math and geography. It's also a pretty good skill to accept if you lot spend much fourth dimension in the wild, as well just being a fun thing to practice (once you get the hang of information technology!). It helps if yous're the kind of person that tin can visualize the landscape from a set of more-or-less capricious symbols (i.eastward. a map!).
There are two main approaches to using maps and a compass.
1. Detect your way through the mural, or
ii. Describe the area of a characteristic IN the landscape.
The first approach involves a predetermined direction or ready of directions. The 2nd arroyo involves the discovery of a set of directions. An example of approach one would be to run a forest inventory filigree through an ownership. Or, to find your way from the motorcar to a hunting stand, already marked on a map. An example of approach ii, would be to calculate the area of swamp or a timber sale area. In either case, you lot likewise have to have some mode to measure distance while you travel. For general approximations, a person's pace is a reasonable method, if you know your stride and have had enough practice to make information technology reliable. Establishing your step is discussed beneath.
Why the Old Technology?
Actually, in most cases, using a GPS (Global Positioning Arrangement) unit can be mighty handy. It has many options. However, there are a couple of downsides that tin can give a map and compass an advantage.
1. Maps and compasses don�t have batteries that die (which will virtually e'er happen while you�re the farthest away from anything that looks familiar!).
two. Maps and compasses are a LOT cheaper than a GPS unit.
3. Compasses can be used under dense forest canopies that will block satellite conquering from most GPS units.
Going From Point "A" to Signal "B"
Measuring An Expanse in the Landscape
Determining Your Pace
A Note Nigh Compasses
True vs. Magnetic North
Going From Indicate "A" to Point "B"
Exercise Proposition: From a marked indicate in a field side by side to the school (or several marked points), students can "discover" what a series of azimuths "signal to" from that marker (i.eastward. water belfry, prominent edifice, flag pole, etc.). If "pace" is used, less obvious markers can be placed in the field for students to "find" using a given azimuth and distance.
This is probably the most mutual apply of a compass. Information technology assumes that you already know where you are on a map and that you know where (on a map) that y'all want to become. You must start discover the azimuth of the line connecting Signal "A" and Point "B". This can be done with a standard map compass or with a protractor. Once in the field, you lot set your compass to the pre-determined azimuth and use the compass to maintain your direction until y'all find Point "B" in the field.
i. Turn the compass wheel (bezel) until "N" is next to the notch in the front of the compass.
2. Orient the map to the compass. Line up the edge of the compass with the edge of the map. Rotate both map and compass together until the magnetic needle is aligned with the "painted" needle under the compass housing. The map is at present oriented and then the "north" side is really pointing north. Don't move the map anymore! Merely you tin can motion the compass.
3. Line upward the border of the compass along the route you wish to follow from Point "A" to Point "B". You'll have to move the compass. Exist sure the front end of the compass is going the aforementioned direction that you want to travel.
4. While belongings the compass firmly against the map, turn the housing until the "magnetic" needle is directly above the "painted" needle. Read the azimuth at the notch in the forepart of the compass wheel. That is the azimuth y'all must follow in the field.
Note: If you use protractors (cheaper than compasses), you do non accept to orient the map. All the same, y'all do need to imagine a 360 degree assortment first from your Point "A". The protractor can exist used to identify which "ray" (in degrees) describes the line from Points "A" to Point "B". This may involve some improver or subtraction depending upon the protractor design and orientation of your directional line.
5. Stand at Point "A" in the field (a known place on the map that is easy to find in the field).
six. Cheque to exist certain that your compass bicycle is set to the pre-determined azimuth (azimuth on the wheel is side by side to the notch in the forepart of the compass).
7. Keeping the compass flat and in front end of y'all, plow your body until the magnetic needle is straight in a higher place the painted needle. The compass is at present pointing in the management that yous want to become.
8. Place something in the altitude that is in-line with where the compass is pointing (not in line with the management the magnetic needle is pointing!).
9. Walk towards that "something". Regularly bank check your compass (step vii) to make sure you lot are not straying from the pre-determined direction.
10. Repeat steps 7-nine until you locate Point "B".
Measuring an Area in the Landscape
Exercise Proposition: A simple traverse can be set upwards in an open field side by side to the school by marking the turning points with wire stakes or other markers. More than ane simple traverse tin be set up, with a team of students at each traverse, or a squad of students start at different turning points of the aforementioned traverse.
This is called a "traverse". Substantially, a series of lines are measured (azimuth and distance) in the field that encloses whatsoever information technology is that you want to measure the area for. Beginning from a known bespeak on a map, await to where you lot want to go, record the azimuth of that direction earlier yous go, and measure the distance between where you are and the next point.
To mensurate an azimuth in the field, bespeak the compass in the direction you lot wish to become. Without moving the base of operations of the compass, turn the compass wheel until the magnetic arrow is straight to a higher place the painted needle. Read the azimuth next to the notch in the front of the compass. Walk to the next point, following the azimuth and measuring the distance (often past counting paces, see below).
Go along to tape compass "legs" effectually the area until you render to where you lot began.
Back in the classroom, use your compass or a protractor to draw the "polygon" onto a map (be aware of the scale of the map!). The traverse will probably not close exactly. Not to worry, merely the closer the better. The surface area of the polygon can be calculated using a " dot filigree " or other area measurement devices calibrated to the map scale.
Dot Grids: A dot grid is a tool used to estimate the area (usually acres) of a polygon on a map. It is simply a transparent sheet with dots marker the imaginary intersections of a regular line grid. Each "dot" that falls within the map polygon represents a unit of area. The dot grid tin exist calibrated to the map by counting the number of dots within a known polygon on the map, and dividing the number of acres by the number of dots (i.e. forty acres / 22 dots = ane.viii acres per dot).
Determining Your "Step"
A footstep is two steps. A count of paces should begin with the left foot, and counts made each time the correct pes falls. Every person volition have different number of paces in a given distance and different number of feet per pace. To determine an individual pace, mark a altitude of 100 feet (outside or in a long hallway). Have the students walk the distance several times, counting their paces. Make sure everyone walks ordinarily, not trying to stretch or shorten their footstep. Average the counts. Divide that average into 100. That is how many feet a student'south step is. Equally students "pace" distances in field exercises, they simply multiply their pace (altitude) by the number of paces they counted.
For example, a student may average 21.five paces in 100 feet. Their pace would measure out 4.6 feet. If they paced an unknown distance for a count of 76 paces, the distance would exist 4.6 x 76 = 349.half-dozen (350 rounded) feet.
If long distances need to be "paced", it is easier to count the number of paces in a certain distance, such every bit a chain or a mile. For case, an adult may have 1100 paces in 1 mile. If they walked a count of 650 paces, then 650 / thou would be a distance of 0.59 miles. More commonly, foresters know their number of paces per chain , which is a land survey unit of measurement of 66 feet. As the forester walks across the landscape, information technology is fairly easy to measure out altitude by dividing a footstep count by their known number of paces per chain (normally 12 or xiii paces per chain). Furthermore, foresters know to adjust their stride with changes with topography, in deep snowfall, on snowshoes, the time of day, and other conditions. With experience and practice, a walking pace tin become a adequately accurate method of distance measurement.
A Notation About Compasses
There are many types of compasses. However, the most useful compass for orienteering consists of a clear plastic rectangular base with a raised bicycle containing a magnetic needle. The wheel can turn. The outside of the wheel has marks for the 360 degrees of a circumvolve, or more commonly has marks for each ii degrees.
Some compass wheels accept four circle quadrants, each labeled from 0 to 90 degrees. This is a bearing compass (image on the left). Don't use them. Information technology's too confusing. Apply an azimuth compass, which uses 360 degree labeling.
True vs. Magnetic North
Nosotros all know that magnetic north is unremarkably non quite true northward. Truthful north is the direction from wherever you are to the north end of the Earth's axis. The magnetic field of the World is normally not aligned with true northward. The amount that magnetic north varies from truthful northward is variable. The line of zero degrees declination is called the "agonic line."
The difference between "true north" and "magnetic north" is chosen declination . In Michigan, declination varies from zero (true north equals magnetic due north) nearly Ironwood and Benton Harbor, to about six degrees west in Sault Sainte Marie and Detroit. Amend compasses accept a characteristic where declination can be adjusted to remove the bias of magnetic north. For most compasses with a congenital-in declination adjustment, the compass wheel should exist turned clockwise (in Michigan). To make matters more than complex, the Earth's magnetic field is not static. Declination lines change over time.
Lastly, there are local magnetic anomalies that can render compasses next to useless. Iron ore deposits in parts of the U.P. will brand compasses acquit erratically. However, most of the time, it pays to follow the compass even when it doesn't quite seem correct.
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